· dev tools + references
Dev tools, in one place.
Free browser-only developer utilities — a live regex tester with cheat sheets (including Python), a UUID generator covering v1 through v7, and a bidirectional JSON ↔ CSV converter with Excel-compatible output. No signup. No server round-trip. Nothing uploads.
Tools.
· interactive · browser-only
· tool · 2026-04-21
Regex tester
Live match highlighting, capture groups (numbered + named), replace mode, and six flag toggles (g / i / m / s / u / y). ECMAScript flavor, browser-only, no signup.
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· tool · 2026-04-21
UUID generator
Generate v4 (random), v7 (time-sortable, RFC 9562), v1 (legacy), or nil UUIDs. Bulk up to 1,000. Four format options (standard / braces / no-hyphens / UPPERCASE). Cryptographically secure via Web Crypto.
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· tool · 2026-04-22
Base64 encoder / decoder
Bidirectional text ↔ base64 with UTF-8 awareness (emoji, accents, CJK), standard and URL-safe variants, file upload for binary encoding, and live image preview for decoded PNG/JPG/GIF/WebP.
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· tool · 2026-04-21
JSON ↔ CSV converter
Bidirectional JSON ↔ CSV with nested-object flattening (dot notation), five delimiters, quote styles, Excel BOM, and line-ending selector. File upload, download, copy.
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· tool · 2026-04-21
JSON to Excel
Same JSON ↔ CSV tool, Excel-forced defaults — UTF-8 BOM on, CRLF line endings, always-quoted fields. Download a .csv that Excel opens correctly on the first double-click.
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· tool · 2026-04-21
CSV to JSON
Paste CSV, get a pretty-printed JSON array of objects. Handles quoted fields, escaped quotes, newlines inside cells. Auto-parses numbers and booleans so the output is immediately usable.
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References.
· cheat sheets · syntax reference
· reference · 2026-04-21
Regex cheat sheet
Every metacharacter, quantifier, anchor, character class, group type, and look-around — with eight production-grade patterns (email, phone, URL, date, IPv4, hex color, whitespace, trim).
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· reference · 2026-04-21
Python regex cheat sheet
Every method of Python's re module (search / match / fullmatch / findall / finditer / sub / subn / split / compile / escape), every flag, and the syntax differences from JavaScript regex.
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Why these, and why browser-only
Every developer has a pinned tab for a regex tester, a UUID generator, and a format converter. Most of those tabs point at sites that want your email, nudge you toward a signup, or quietly send your data somewhere for analytics. The browser can do all of this work locally — the regex engine is native, UUID generation is in the Web Crypto API, parsing CSV is about 40 lines of JavaScript — so there's no real reason to upload anything.
The tools here are the ones we use daily. They're deliberately narrow. The regex tester is ECMAScript-flavor only (not PCRE, not Python, not Java) because that's what most devs are writing regex for when they open a browser tab, and because shipping five flavors means maintaining five engines. The UUID generator doesn't try to pretend it can give you a real MAC-based v1 — the browser can't see your MAC, so the node portion is random and we say so. The JSON ↔ CSV converter handles nested objects with dot notation because that's what people actually want.
Missing a tool? Email us — the next thing we ship is usually whatever a developer asked for twice in a week.