The dev toolbox.
Always local.
Eighteen hand-picked utilities that replace half a tab of online tools. JSON, JWT, regex, hashes, SQL, cron, contrast, QR codes and more. All client-side, all the time.
No payload leaves your browser. Paste production tokens with confidence.If you spend half your day in the network tab and the other half wrangling strings, this is your shortcut. Every tool here runs the same algorithm as openssl, jq or jsonlint, just without the middleman. Paste, inspect, copy. No login needed.
The dev essentials
18 toolsJSON Formatter and Validator
Pretty-print and validate JSON live as you paste. Spot a missing comma in milliseconds, no upload to a third-party.
Regex Tester (JavaScript Flavor)
Test JavaScript regexes against real input with match highlighting and capture-group breakdown. Spot slow patterns before they hit production.
JWT Decoder
Decode header and payload of any JWT to inspect claims, scopes and expiry. Signature stays unverified, this is a debug tool not a validator.
Base64 Encoder and Decoder
UTF-8 safe Base64 with URL-safe variant. Useful for inspecting JWT segments, building data URIs, debugging Basic auth.
URL Encoder and Decoder
Component vs full URI mode. Decide whether you want :/?#&= encoded as well or left alone. No more guessing what your endpoint expects.
UUID v4 Generator
Bulk generation of cryptographically random UUID v4 (uses crypto.randomUUID). Handy for seeding test fixtures and migrations.
SHA Hash Generator
Live SHA-1, SHA-256, SHA-384 and SHA-512 via Web Crypto Subtle. The same digests as openssl or sha256sum byte-for-byte.
Unix Timestamp Converter
Drops a Unix timestamp or ISO string and shows seconds, milliseconds, ISO, UTC, local and relative. Auto-detects the input format.
CSV ↔ JSON Converter
Bidirectional CSV ↔ JSON with quoted-field support. The fastest way to inspect a spreadsheet export as an API payload.
HTML Tag Stripper
DOMParser-backed HTML to plain text. Drops scripts, styles and noscript. Use it to extract readable copy from a CMS export.
Text Diff Comparator
Line-level LCS diff between two texts with green / red colour coding. Faster than firing up git for a quick review.
Color Converter (Hex / RGB / HSL)
Hex / rgb / hsl with alpha and live swatch. Round-trip a brand colour through any CSS notation without breaking.
SQL Formatter
Reformat any SQL across 12 dialects (PostgreSQL, MySQL, BigQuery, Snowflake, T-SQL...). Pick keyword case and indent, no upload.
Cron Expression Builder
Visual cron builder with one-click presets and a plain language description below. Stops you guessing at /5 vs */5 in production.
Markdown to HTML and HTML to Markdown
Bidirectional Markdown to HTML and HTML to Markdown with GFM. Convert a README to a static page, or import a CMS export back to Markdown.
WCAG Contrast Checker
WCAG AA and AAA contrast for text and background, with a live preview. Validate brand colours before you ship the design system.
Date Difference Calculator
Days, weeks, working days and a years/months/days breakdown between any two dates. Doubles as the age calculator nobody wants to write again.
QR Code Generator
Browser QR codes with custom colours, error correction and SVG download. Wi-Fi and vCard formats baked in.
Power workflows
Pretty + minify in one tab
Paste a minified JSON, hit Format, copy. Then switch the action to Minify, copy the compact version. Keep both ready for a PR description.
JWT debug pipeline
Copy the JWT into the decoder, take the iat / exp / nbf numbers from the payload, paste them into Timestamp Converter for human-readable expiry. No backend roundtrip.
CSV to clean data fixture
CSV → JSON, then JSON Formatter to pretty-print, then Find and Replace to scrub PII before committing the fixture.