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The Client-Side Sandbox
No LLM costs. No accounts. Just pure code utilities — running entirely in your browser.
$ requests sent after page load:
0
$ your data uploaded to a server:
never
— everything runs on your CPU. that’s the whole trick.
Zero friction
No sign-in walls, no pricing tiers, no upgrade banners. Every tool is live and interactive the millisecond the page loads.
100% local execution
Everything runs on client-side JavaScript. Paste JWTs, corporate payloads, or private configs — your data never leaves this browser tab. Check the network panel; we dare you.
Infinite iterations
No tokens, no credits, no metered anything. Run ten thousand variations, test edge cases for hours — it all executes on your CPU, for free, forever.
The workshop
Every tool below runs locally. Pick one and get to work.
JSON Formatter
Validate with exact error locations, beautify, minify & query by path.
JWT Decoder
Decode header, payload & expiry — with a live session-death simulator.
Regex Tester
Live match highlighting, flags, and a plain-English token breakdown.
Base64 Encode / Decode
Text & files to and from Base64 — UTF-8 safe, with live image preview.
CSV → JSON Mapper
Map columns to typed JSON, then minify & truncate for LLM prompts.
Diff Checker
Side-by-side diff with a semantic JSON mode that ignores key order.
URL Encoder / Decoder
Escape and unescape URLs and query strings correctly.
UUID Generator
Generate v4 UUIDs in bulk using your browser’s crypto API.
Cron Expression Parser
Translate cron to plain English with your next 5 run times.
Hash Generator
MD5, SHA-1, SHA-256 hashes computed locally via WebCrypto.
Timestamp Converter
Unix epoch to human-readable and back, any timezone.
Markdown Preview
Live GitHub-flavored markdown rendering as you type.