Toolbox

What would you like to check or calculate? Here you will find small tools for technical tasks, from Base64 and JSON to network planning and music production. Describe what you want to do below, or search the catalogue by name or topic.

144 tools in 13 groups

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Start with a task

One problem, a clear way through

Understand the issue, try a tool and put the result in context. These three starting points connect articles with useful tools.

My JSON is causing trouble

Understand: Check a JSON payload
Try it: Format JSON
Start with a small example and find syntax errors. Then check whether the values and types fit your application – valid syntax alone cannot tell you that.

What is inside this token?

Understand: Understand JWTs
Try it: Inspect a demo token
Inspect a demo token and understand its fields. Readable claims do not prove a valid signature or permission to access anything.

I want a clean music export

Understand: Clipper or limiter?
Try it: Measure loudness and peaks
Check the loudness and peaks of your export. Measurements help with comparisons; listening and considering your source material still matter.

Search tools

Featured tools

New

SaaS Profitability Calculator

Monthly profit, minimum price and break-even including payment, API and support costs.

Featured

GTM Container History & Deep Search Engine

Search every Google Tag Manager container version for tags, triggers, variables, templates, and folders without manual file exports.

New

Cache-Control & Revalidation Analyzer

Reads the caching headers of an address, works out how long a browser and a shared cache may keep the response and on what basis, sends conditional requests to see whether ETag and Last-Modified really produce a 304, and checks whether a CDN or page cache in front is hitting.

New

GA4 Measurement Protocol JSON Validator: see every fault at once

Reads a Measurement Protocol payload against the documented rules and reports every fault in one pass: reserved names, silent length limits, timestamps in the wrong unit, personal data in parameters, item sums that disagree with value. The same payload also goes to Google’s own validation server twice — strict and the way production treats it — so the gap between the three verdicts is visible side by side.

New

Compression Negotiation Checker: gzip, Brotli, zstd

Fetches an address five times with different Accept-Encoding values and shows what the server actually sends: which encodings it offers, how many bytes cross the wire for each, what a browser's combined header gets, and whether Vary and ETag keep caches from mixing them up.

New

HTTP/3 & Alt-Svc Discovery Checker

Fetches an address over HTTP/1.1, HTTP/2 and HTTP/3 from this server, reads the DNS HTTPS record and the Alt-Svc header, and shows how a browser on a first visit finds out that HTTP/3 exists, whether QUIC actually answers, and what a second visit negotiates.

SaaS & Internet Earning 9

SaaS Profitability Calculator

Monthly profit, minimum price and break-even including payment, API and support costs.

SaaS Pricing Model Simulator

Compare subscriptions, credit packs and outcome pricing across three usage profiles.

Automation Cost Comparator

Compare n8n, Make and custom code using operating costs, billing units, maintenance and setup.

MRR and Churn Simulator

Project monthly recurring revenue, new customers, churn and price changes over up to 60 months.

Digital Product Profit Calculator

Calculate contribution margin, minimum price and break-even for templates, data packs and mini-tools.

SaaS Customer Acquisition Calculator

From visits to payments: expected new customers, acquisition cost and recovery of sales spending.

SaaS Cash Flow and Runway Simulator

Monthly cash receipts and cash balance with monthly and annual plans, churn and refunds.

AI Usage Budget Calculator

Check token cost, retry attempts and peak usage against a monthly cost budget per customer.

SaaS Support Capacity Planner

Plan ticket volume, handling time, available capacity and support cost per customer.

Google Analytics 4 & BigQuery 20

BigQuery GA4 Query & UNNEST Builder

Generate optimized standard SQL for GA4 BigQuery exports with automatic UNNEST parameter logic.

E-Commerce Anomaly Threshold Planner

Turns an event volume into a usable alert threshold: how many false alarms a sigma rule produces per day, and the smallest drop it is able to see at all.

GA4 Advisor & runReport Verifier

Checks a structured Analytics Advisor answer against two independent GA4 Data API reports for the same periods, metric and dimension. A matching cell confirms that value, not the AI explanation.

GA4 Anomaly Detector

Detect sudden spikes and drops in standard GA4 metrics via the Analytics Data API using Z-score analysis.

GA4 API Response Inspector

Explains report metadata, quota usage and warnings from a pasted GA4 Data API response (runReport, batchRunReports). Runs in the browser without a Google login.

GA4 BigQuery Query Builder

Builds a query against the GA4 export schema with the correct UNNEST form per parameter, a date filter that actually prunes tables, and the traps that quietly change the result.

GA4 Bot Detector

Reviews reported GA4 traffic groups using explicit cues. No bot probabilities or identity verification. Read-only Google access and CSV export.

GA4 Channel Grouping & Unassigned Debugger

Shows which default channel group GA4 assigns to a source, medium and campaign, which of the eighteen rules matched, and why a session ends up in Unassigned.

GA4 E-Commerce Item Array Validator

Validate GA4 e-commerce item arrays against specification rules and inspect calculated monetary totals.

GA4 Event Parameter Generator

Generate a ready-to-paste dataLayer.push code block from GA4 standard events and custom parameters.

GA4 gcd Parameter Decoder

Decode cryptic GA4 gcd consent parameter strings into actionable storage states and update origins.

GA4 Measurement Protocol JSON Validator: see every fault at once

GA4 Measurement Protocol Payload Builder

Build and validate JSON payloads and cURL requests for GA4 Measurement Protocol server-side testing.

GA4 Parameter Analyser

Break a GA4 request URL or POST payload into individual parameters and lay out the e-commerce items it carries.

GA4 Property Configuration & Snapshot Comparator

Reads a defined set of GA4 settings, such as data retention and key events, with read-only access and compares two properties or two saved snapshots. Saved snapshots can be compared without a Google login.

GA4 Thresholding and Behavioural Modelling Checker

Behavioural modelling needs granted users and denied events at the same time, so it lives inside a consent-rate corridor rather than above a single threshold. This calculates that corridor, and how much of a report's long tail thresholding removes.

Looker Studio Blend & Join Planner

Works out how many rows a blend produces and by which factor a metric of the left table is inflated before the numbers reach a chart.

Matomo Tracking API & Custom Dimension Builder

Assembles a request to the Matomo HTTP Tracking API with page views, events, goals and custom dimensions, and points out the mistakes that make a hit disappear without an error.

Report Date Coverage Checker

Checks a daily CSV series for missing, repeated and out-of-period dates, optionally next to a second period. For exports from GA4, YouTube Analytics and other reporting APIs; runs locally in the browser.

Shop vs. GA4 Revenue Reconciliation

Matches a shop order export with a GA4 export by exact transaction ID and lists missing orders, duplicate IDs, amount differences and currency mismatches. Files stay in the browser.

Tag Manager, Server-Side & Ads 12

Conversion Window and Audience Duration Calculator

Widening a conversion window raises the reported figure without a single extra sale, a short window on one class of touch quietly drops the rest, and an audience list is its daily inflow times its duration. Three settings, three arithmetic consequences.

DataLayer Inspector & Validator

Validate the syntax of a dataLayer.push object and lay out every key and value in a readable table.

GoogleAds – GAQL Query Explorer

Format Google Ads GAQL queries and inspect their SELECT, FROM, WHERE, and LIMIT structure locally in the browser.

GTM Container History & Deep Search Engine

Search every Google Tag Manager container version for tags, triggers, variables, templates, and folders without manual file exports.

GTM DataLayer Variable Path Flattener

Flatten nested dataLayer JSON structures into copy-ready dot-notation paths for Google Tag Manager variables.

GTM Duplicates Analyser

Find variables and triggers that share identical configuration logic inside a GTM container export.

GTM Naming Convention Auditer

Audit a GTM container export for tags and triggers that miss one of the required naming prefixes.

Meta & TikTok CAPI Dedup & Hash Generator

Normalize user contact data and simulate Event ID deduplication payloads for Meta and TikTok CAPI.

Meta CAPI Match Key Planner & Hasher

Shows which customer parameters a Conversions API event carries, how far that gets the match, and what each value has to look like before it is hashed. Everything runs in the browser.

Server-Side GTM – Cloud Run Cost Estimator

Estimate monthly Google Cloud Platform (GCP) Cloud Run infrastructure costs for Server-Side Google Tag Manager (sGTM).

Set-Cookie Analyzer & ITP Lifetime Simulator

Reads a Set-Cookie header, checks the attributes browsers reject outright, and shows how long the cookie really survives in Safari, Chrome and Firefox.

UTM Campaign Link Builder & Strict Linter

Generate GA4 tracking campaign URLs with live linting and strict enforcement of lowercase, URL encoding, and underscores.

Consent & Data Privacy 10

Connection Mirror: What the Server Sees

Shows what this server learns from a visit before any script runs: the address and its network owner, TLS version and cipher, HTTP version, every request header including Global Privacy Control, Do Not Track and Client Hints, and compares it with what the browser itself reports.

Consent Mode v2 Decoder

Decode the gcs parameter from a GA4 request and reveal whether ad storage and analytics storage were granted or denied.

Email Tracking Pixel and Remote Content Auditor

Lists everything in an email that reaches a server the moment the message is opened: invisible pixels, background images, wrapped links and the identifiers that tie an open to one person. Parsing happens locally and fetches nothing.

GA4 PII Checker

Scan the page reports of a GA4 property via the Analytics Data API for personally identifiable information in URL parameters.

IP Anonymization & Masking Tester

Shows what an IPv4 or IPv6 address looks like after truncation, how large the remaining group of addresses is, and whether a payload carries a private address instead of the visitor's.

Privacy Sandbox and Fingerprint Surface Detector

Reads the running browser: which Privacy Sandbox interfaces still answer, which of the three survivors are present, and how much of the high-entropy surface this page is handed. The answer differs by browser, which is the point.

TCF v2.2 Consent String Decoder

Decode an IAB TCF v2.2 consent string entirely in the browser: CMP, purposes, legitimate interest, vendors, publisher restrictions and the checks that TCF 2.2 made stricter.

Tracking and Consent Scanner for a Live Page

Fetches a page and lists what it brings along: which measurement and advertising tags are wired in, which consent tool sits in front of them, whether anything is actually held back, and which cookies the very first response already sets.

Usercentrics DataLayer Event Simulator

Simulate Usercentrics consent choices and inspect live dataLayer payloads and GTM tag firing logic.

Web Font Loading & Privacy Auditor: font-display, woff2, preload, third-party origins

Fetches a page and its stylesheets, reads every @font-face rule and checks what actually costs time or privacy: whether font-display is set at all, whether the file comes from a third-party host, whether woff2 is offered, whether subsetting is used, and whether a preload for a font carries crossorigin. Font files are never downloaded — only their headers are asked for.

Web Security 11

Authentication: Basic Auth + htpasswd Generator

Generate a .htpasswd entry, a Basic Auth Authorization header, and a matching cURL test command, entirely in the browser.

CSP Header Generator & Tracking-Linter

Generate standard Content-Security-Policy (CSP) headers with preset permissions for GA4, GTM, Matomo, and Server-Side endpoints.

Domain RDAP & Certificate Transparency Lookup: Registrar, Expiry, Forgotten Subdomains

Asks the registry via RDAP who a domain is registered with, when it was created and when it expires, which status locks apply, which nameservers serve it and whether DNSSEC is delegated, then reads Certificate Transparency logs for every host name a certificate was ever issued for, including subdomains nobody remembers.

Email Authentication Checker: SPF, DKIM, DMARC, MX and CAA

Reads a domain's DNS and says what actually happens to a forged message: how many of the ten allowed SPF lookups are used up, whether DKIM keys are long enough, and whether DMARC tells anyone to do something or merely watches.

HSTS & Preload Readiness Checker: the four addresses that decide it

Looks at http and https, each with and without www, and reads only the status line, the redirect target and the Strict-Transport-Security header. Redirects are deliberately not followed, because the first hop is what decides: a jump straight from http://example.com to https://www.example.com disqualifies a domain from the preload list, and it is the most common reason submissions are rejected.

HTTP Security Header Checker

Reads the response headers of an address and says what they actually do: a policy with unsafe-inline is present and toothless, an HSTS of five minutes protects nobody, and a missing frame rule is a missing frame rule.

JWT & OAuth Token Inspector

Decodes a JSON Web Token in the browser, works out how long it is still valid, lists its scopes and points out a missing signature, an endless lifetime or personal data in the payload.

Mail Transport Security Checker: MTA-STS, TLS-RPT, DANE and STARTTLS

Checks what a sending mail server finds when it delivers to a domain: the MX hosts, whether STARTTLS is offered and which TLS version and certificate come back, whether an MTA-STS policy and a TLS-RPT address exist and are consistent, and whether DANE records match the certificates.

Third-Party Origin & Subresource Integrity Checker: who a page loads from, and what it trusts

Fetches a page once and sorts everything it pulls in by three questions: which host it comes from, whether it travels over http on an https page, and whether a third-party script or stylesheet carries an integrity attribute. One request is enough, because the answers are in the markup — which also means anything a script loads later stays invisible.

TLS Certificate & Handshake Inspector

Opens a TLS connection to a host and reads what the browser never shows in full: certificate names and expiry, the chain and whether it verifies, key and signature, the negotiated protocol and cipher, and which TLS versions the server still accepts.

Well-known & Policy Files Inspector: security.txt, ads.txt, gpc.json, llms.txt

Fetches the thirteen policy files a domain can publish at fixed paths, from security.txt and robots.txt to ads.txt, gpc.json, llms.txt, change-password, assetlinks and the Apple app association, and checks each against its own rules: present, expired, soft 404, wrong content type, unreadable.

Performance & Delivery 5

Cache-Control & Revalidation Analyzer

Compression Negotiation Checker: gzip, Brotli, zstd

HTTP/3 & Alt-Svc Discovery Checker

Image Delivery & Format Negotiation Auditor: WebP, AVIF, srcset, Vary

Fetches a page, takes the first images from its markup and asks the server for each one twice: once as a browser that accepts WebP and AVIF, once as one that does not. The comparison shows whether formats are negotiated at all and whether the answer carries Vary: Accept, without which a shared cache hands the modern file to a browser that cannot read it. Markup is checked alongside: width and height, srcset, loading and alt.

Script Loading and Execution Order Analyzer: what a script sees when it runs

Reads every script tag of a page in document order, sorts them into blocking, defer, async, module and data, and measures the one number that decides how much a blocking script can see: how far into the document it sits, and how many bytes of markup are still unparsed at that moment. Nothing is rendered.

SEO & Crawlers 16

301 Redirect Rule Generator (.htaccess, nginx, WordPress)

Turns a list of old and new addresses into redirect rules for Apache .htaccess, nginx or a WordPress hook. Merges pairs that share a folder change into one prefix rule, flattens chains so every old address points at its final target, and refuses loops and contradictions before they reach the server.

AI Citation and Website Traffic Comparator

Matches AI citations per URL (for example from Bing AI Performance) against sessions per URL from a second CSV and shows pages that appear in only one of them. Two separate measurements, not a click-through rate; files stay in the browser.

Canonical, hreflang and Indexing Signal Inspector

Reads what a page tells a search engine about itself: which address it declares canonical, what its robots directives say, whether robots.txt lets the crawler in at all, and which of those four can quietly cancel the others.

Crawler IP Verifier: Googlebot, Bingbot, GPTBot and Others

Takes an IP address from a server log and checks whether it really belongs to the crawler it claims to be: reverse DNS with forward confirmation, the address lists Google, Microsoft, OpenAI, Apple, Perplexity and Ahrefs publish, and the network owner from RDAP.

JSON-LD Structured Data Generator & Checker

Builds JSON-LD for Article, FAQPage, HowTo, Product, Organization and BreadcrumbList, and checks existing markup for the mistakes that quietly cost a rich result.

Live JSON-LD Structured Data Validator: what a page actually declares

Fetches a page, pulls out every ld+json block and reads the nodes one by one: does the JSON parse, does each node carry @context and @type, are the fields search engines expect present, are URLs absolute and dates machine-readable, and does a breadcrumb list hold together without gaps. One request, and only what the server sends.

Open Graph & Social Card Checker: og:image, Twitter Card, Link Preview

Fetches a page, reads its Open Graph and Twitter Card tags, downloads the og:image and measures it, then renders the link preview the way messengers and social networks would: title, description, image and host, with findings on size, aspect ratio, weight, absolute URLs and missing tags.

Page Structure & Readability Inspector: Headings, Sentences, Abbreviations

Fetches a page and measures its structure instead of its style: title, description and language, the heading tree with gaps and empty headings, the main content landmark, words, paragraphs and sentence lengths measured strictly inside paragraphs, unexplained abbreviations in the introduction, images without alt text, links and building blocks.

Redirect Chain & Canonical Host Tracer

Follows an address hop by hop and shows every station with status code, Location and timing, then tries the four variants http/https with and without www to see whether they all land on the same page. Flags loops, chains, 302 where 301 belongs and https to http downgrades.

robots.txt & llms.txt Generator for AI Crawlers

Writes a robots.txt that separates search engines, AI training crawlers and AI assistants, plus an llms.txt skeleton, and explains what each block really achieves.

robots.txt Crawler Matrix: which rule wins for which bot

Reads a site's robots.txt, resolves every user agent to the group that governs it, and shows for each path whether crawling is allowed and which rule decided it. Includes the part most summaries get wrong: what a 404, a 410 or a 500 on the rules file itself means for a crawler.

RSS & Atom Feed Checker: findable, well-formed and alive?

Reads the feed links from a page, fetches them and checks what a feed reader needs: well-formed XML, a content type nobody has to guess, entries with an address and a date, and a self link so the feed knows where it lives. When no feed is linked, two common paths are tried — a feed nobody links to is practically invisible.

Sitemap Checker & Validator: Schema, hreflang, Image, Video and News Extensions

Checks an XML sitemap or sitemap index in the browser against sitemaps.org and Google's extensions: well-formedness with line and column, namespaces, required fields, lastmod, limits, hreflang with return links, and image, video and news tags.

Soft 404 & Error Page Checker: what a site answers for an address that does not exist

Asks three addresses that cannot exist — one without an extension, one ending in .html and one ending in a slash — and compares the answers with a page that does exist. A missing page answering 200 is the quiet failure: search engines index it, link checkers stay silent, and nobody notices the broken links.

Web Bot Auth Signature Inspector and Crawler Range Checker

Takes the two ways a site can tell who is asking and puts them side by side: an Ed25519 signature per RFC 9421, rebuilt and verified against a public key, and a list of published address ranges, counted and tested for containment.

XML Sitemap Auditor: Index, lastmod and a Sample Check

Finds a site's XML sitemap via robots.txt or the default paths, follows a sitemap index to its children, checks the entries for lastmod quality, foreign hosts, duplicates and size limits, and fetches a sample of twelve listed pages to see whether they answer 200, redirect, carry noindex or point their canonical elsewhere.

WordPress 6

WordPress Dequeue Snippet Generator

Turn a list of script and style handles into a ready-to-paste functions.php snippet that unloads them where they are not needed.

WordPress meta_query JOIN Analyzer

Counts the JOINs a meta_query produces, marks the clauses that cannot use an index, and generates a custom table with the matching query as the way out.

WordPress REST Route & Permission Callback Generator

Generate the register_rest_route scaffold with an argument schema, sanitize and validate callbacks, and a matching permission callback.

WordPress REST Route Inventory: what a site hands out without a login

Reads the route directory under /wp-json/, counts routes and namespaces, and then fetches ten well-known routes without any credentials — because the directory only says which routes exist, never who is allowed to read them. Only that second step separates a listed route from an open one.

WordPress Site Health Analyzer

Enter one address and get a scored optimisation report for a WordPress blog or WooCommerce shop: page cache, compression, HTTP/2, render-blocking scripts, image loading, cart fragments on every page, version leaks and open XML-RPC. Reports are kept for a day; a button re-checks after changes.

WP-CLI Database Cleanup Command Builder

Assembles the WP-CLI commands for a database cleanup, puts a counting command in front of every deletion and names what each step cannot bring back.

Networking & Self-Hosting 11

Backup Retention & Transfer Window Planner

Size a GFS backup scheme: the target storage the retained copies occupy and how long full, daily, and restore transfers take over the uplink.

DNS Delegation, Serial & TTL Auditor: asking every nameserver separately

Asks a public resolver for the delegation and then queries each authoritative nameserver directly. Only the second step reveals the failures a normal lookup never shows: one server holding an older copy of the zone, one still listed but no longer answering for it, or all of them sitting in the same network.

Multi-WAN Failover & Policy Planner

Works out how long a failover actually takes, how long a backup data cap lasts, and which policy routes are shadowed by the one above them.

Pi-hole / AdGuard Blocklist Converter & Overlap Analyzer

Merge Pi-hole and AdGuard blocklists, convert them between hosts, dnsmasq, and AdGuard syntax, and measure how far they overlap.

Prometheus Time Series Capacity Planner

Turns exporters and scrape interval into disk, memory and write load - including what a year of scraping does to the card a Raspberry Pi boots from.

Raspberry Pi Docker Compose Edge Linter

Lint Docker Compose configurations against edge server best practices including timezones and restart rules.

Traefik Label & Compose Generator

Writes the Traefik labels for a container - router, service, TLS and middlewares - and names the pitfalls that leave a service unreachable or unprotected.

UniFi / IoT VLAN Subnet & CIDR Calculator

Calculate usable IP host ranges, broadcast addresses, and VLAN segmentation layouts for home networking.

UniFi PoE Power Budget & Load Calculator

Calculate total power draw across PoE hardware and verify switch capacity saturation for UniFi deployments.

UniFi Zone Matrix Planner

Turns a set of network zones into a matrix of policies, derives the rule list from it, and points out the openings that undo the segmentation.

WireGuard AllowedIPs & Split-Tunnel Calculator

Build AllowedIPs for a WireGuard peer: carve excluded networks out of a range and reduce the rest to the smallest CIDR set.

Smart Home, CCTV & Energy 10

CCTV Lens, Field of View & Pixel Density Calculator

Turns sensor size, focal length and distance into field of view and pixels per metre, and says which DORI level a camera actually reaches.

CCTV Storage & Network Bitrate Calculator

Calculate network bitrate (Mbps) and storage capacity (TB) for CCTV installations based on H.264/H.265 codec and motion retention.

Frigate & Coral TPU Capacity Planner

Adds up the detection load of every camera, compares it against what a Coral TPU delivers, and produces a matching frigate.yml skeleton.

mmWave Presence Zone Planner

Turns distance gates and per-gate sensitivity into the area a LD2410 or LD2450 actually watches - and shows where it reaches through the wall into the next room.

Modbus & SunSpec Register Decoder

Decode raw 16-bit Modbus registers into typed values and compare all four word orders side by side.

MQTT Discovery Payload Builder for Home Assistant

Builds the discovery topic and the config payload for an MQTT entity, and catches the mismatches between device class, unit and state class that keep a sensor out of the energy dashboard.

PV Surplus & Battery Charging Calculator

Splits the current surplus between battery and a switchable load, works out how long the battery needs, and derives the switching thresholds for a surplus automation.

Raspberry Pi Power Draw & UPS Runtime Calculator

Work out the steady power draw of a Raspberry Pi with its peripherals, the remaining supply headroom, and the battery runtime.

RTSP Stream URL Builder & Vendor Reference

Generate standard RTSP/WebRTC stream URLs and Frigate NVR config blocks for Hikvision, Dahua, Reolink, Axis, and UniFi.

Zigbee & Wi-Fi 2.4 GHz Channel Planner

Puts the sixteen Zigbee channels next to the Wi-Fi channels already in the air and shows which of them keeps the widest distance from the interference.

AI & LLM 7

GPU VRAM Mod Evidence Checklist

Record offer claims, technical evidence and costs. No authenticity or stability guarantee.

LLM API Token & Cost Calculator

Works out what a language model costs per request, per month and at ten times the volume, splits input, cached input and output, and estimates tokens from a piece of text.

LLM Memory and Hardware Planner

Calculate memory components, context and headroom separately. A sufficient budget establishes neither backend support nor speed.

LLM Model Comparison and Test Log

Compare recorded DE, EN and PL test results under documented conditions. Tests are not run automatically.

Local LLM Software and Setup Planner

Narrow installation paths by operating system, hardware and model format. Record documented prerequisites and verification status separately.

Local vs Cloud LLM Cost Calculator

Compare local hardware, GPU rental and API use for the same task and currency.

RAG Chunking & Embedding Planner

Turns a document set into chunk counts, embedding cost and vector storage, and shows how much of the context window the retrieved chunks take up.

Developer Utilities 12

Base64 Encode & Decode Tool

Encode text or JSON into a UTF-8 safe Base64 string and decode Base64 back into readable text, entirely in the browser.

Code Beautifier – JavaScript, PHP, Python, SQL & More

Reformat minified or messy JavaScript, PHP, Python, SQL, and a dozen more languages with clean, consistent indentation.

Code Minifier – JavaScript, PHP, Python, SQL & More

Minify JavaScript, PHP, Python, SQL, and a dozen more languages by stripping comments, blank lines, and redundant whitespace.

Colour Contrast and Palette Auditor: two themes, one set of names

Takes the CSS custom properties of a light and a dark palette, forms every foreground-on-background pair and measures its contrast ratio against WCAG 2.2. The point of holding both at once: a pair that passes in one theme and fails in the other, and a variable that exists in one palette but not the other.

Crontab – Cronjob Builder & Explainer

Build cron expressions from ready-made presets and read a plain-language explanation of all five fields.

DateConverter – Unix Epoch Timestamp & ISO

Bidirectional epoch timestamp and ISO 8601 date converter for server logs, BigQuery, and tracking APIs.

JSON Beautifier

Format unstructured JSON into readable, syntax-highlighted output, or collapse it back into a single line.

Regex Tester & Explainer

Runs a regular expression against a text, lists matches and groups, and explains the pattern piece by piece, including the constructs that make it slow.

SQL Query Formatter & Parameter Binder

Clean, format, and bind SQL parameters (replacing ? and @param placeholders) for testing queries from application logs.

Text & Code Diff

Compares two versions line by line, marks what was added and removed, and can ignore whitespace, case and blank lines.

URL Decode & Encode Tool

Encode and decode URLs and tracking parameter components instantly using client-side JavaScript.

URL Pretty Print: Anatomy, Encoding and Tracking Parameters

Breaks a URL into every part it is made of, decodes what is encoded, says which parameters are measurement rather than function, reads punycode hosts back into letters, and rebuilds a clean address. Nothing leaves the browser.

Music Production 15

Audio Codec Support in the Browser: which formats this browser plays, streams and records

Asks this browser directly which audio formats it can play through the audio element, stream through Media Source Extensions and record with MediaRecorder, and lists the answer per container and codec with the meaning of “probably” and “maybe”.

Audio Latency Calculator: buffer size, sample rate, milliseconds, round trip and sound travel distance

Converts buffer size and sample rate into latency in milliseconds, adds extra input and output latency, estimates the round trip, shows how far sound travels in the same time, rates the buffer against the FL Studio manual and converts between samples and milliseconds.

BPM to Delay Time Calculator: tap tempo, note lengths in ms and Hz, reverb pre-delay and bar durations

Converts a typed or tapped tempo into note lengths in milliseconds, hertz and samples for straight, dotted and triplet notes, splits a note length into reverb pre-delay and decay and turns bars into a duration.

Click and Splice Finder: find clicks, hard cuts and slope breaks in an audio file

Searches an audio file for clicks, hard cuts and places where the waveform suddenly reverses, using the prediction error of a linear predictor. Lists each place with its time, how far it stands out, its level above 5 kHz and the fade length that buries it, based on a measurement of crossfades.

Gapless Playback Checker: encoder delay and padding in MP3, AAC, Opus and FLAC

Reads an audio file in the browser and reports what the file itself declares about encoder delay and padding: the LAME tag in MP3, the edit list and iTunSMPB in MP4, the pre-skip in Opus, the sample count in FLAC. States how long the gap would be for a player that ignores those fields.

ISRC, ISWC and Barcode Lookup: recordings, works and releases in MusicBrainz

Looks up an ISRC, ISWC, UPC or EAN in MusicBrainz: recordings with artist, length, releases and linked work, works with writers and collecting society IDs, releases with label, catalogue number and format, plus notes on codes that are used more than once.

ISRC, UPC/EAN and ISWC Validator: structure and check digits of release codes

Checks ISRC, UPC, EAN-13 and ISWC codes from a list: detects the type, validates structure and check digits, compares ISRC prefixes with the IFPI list, explains every part and converts between UPC-A and EAN-13.

LUFS and True Peak Meter: loudness, loudness range and streaming normalisation

Measures integrated loudness (LUFS), true peak (dBTP) and loudness range of an audio file in the browser, following ITU-R BS.1770-5 and EBU R 128, and recalculates how Spotify and the AES recommendation would normalise it. The file never leaves the device.

Noise Floor Meter: measure the noise floor in dBFS and get the afftdn setting

Finds the quietest passage of an audio file and measures its noise floor in dBFS, the value the nf control of ffmpeg's afftdn expects. Also shows the noise level below the signal, what denoising gained at that level in a measurement, whether the noise is hiss or hum, and a ready ffmpeg command.

Note to Frequency and MIDI Converter: note names, MIDI numbers, hertz, cents and period at any reference pitch

Converts between note names, MIDI numbers and frequencies in every direction, shows the deviation of a frequency from the nearest note in cents, the period and the samples per cycle, with an adjustable reference pitch and octave numbering as in FL Studio or scientific pitch notation.

Offset and Polarity Checker: time offset and reversed polarity of two tracks

Measures the offset between two tracks, or between left and right, to a fraction of a sample, detects reversed polarity and computes what the sum gains or loses, overall and below 150 Hz. Returns the ffmpeg command that shifts and inverts the second track.

Release File Checker: sample rate, bit depth, peaks, silence, ISRC and cover before the upload

Reads a WAV, AIFF, FLAC, MP3, M4A or Ogg file in the browser and lists what stands between it and a delivery: format, sample rate and bit depth against Apple's requirements, bit padding, clipping, true peak, DC offset, silence and jumps at both ends, and title, artist, ISRC and cover from the tags.

Reverb Clarity Calculator: C50, C80 and modulation depth from decay time, reverb level and pre-delay

Calculates the clarity indices C50 and C80, the definition D50 and how much of the level fluctuation at quarter, eighth and sixteenth notes and at syllable rate survives the reverb, from decay time, reverb level and pre-delay.

Stereo Correlation and Mid/Side Meter: correlation per band, side share, mono compatibility and channel balance from an audio file

Reads an audio file in the browser and measures the correlation between the left and right channel, the level of the side signal against the mid, the loss of a mono sum and the channel balance, in total and in three frequency bands, plus the correlation over time.

Tempo Converter for Time-Stretching: tempo factor, new length and pitch shift

Converts an original tempo into a target tempo for time-stretching: tempo factor for atempo and rubberband, new length in time and samples, beat and bar lengths, the pitch shift of varispeed and the ISRC rule for length changes, with ffmpeg commands based on a measurement.

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