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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 & unescape URLs, with a smart param grid that strips trackers.
UUID & NanoID Generator
Bulk v4 UUIDs & NanoIDs from your browser’s crypto API — up to 5,000 per click.
Cron Expression Parser
Translate cron to plain English with your next 5 run times.
Hash Generator
SHA-256/512, SHA-1 & MD5 side by side — hex or Base64, all local.
Timestamp Converter
Epoch to human & back, with a live ticker and six-zone time machine.
Cloud IP Firewall Matrix
AWS, GitHub & GCP IP ranges as CIDR lists, JSON, or Terraform ingress.
Supabase RLS Builder
Generate valid Postgres row-level-security policies from presets.
Markdown Preview
Live GitHub-dark rendering with tables, task lists & sync scroll.