Code Tools — Free Online Tools
Browser-based developer utilities: JSON formatter/validator, RSA key generator, Base64, hash generator, UUID, regex tester and more. No signup, code never leaves your tab.
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The tools I wish every tutorial linked to.
A practical guide to code tools on DailyTool
In short: Browser-based developer utilities: JSON formatter/validator, RSA key generator, Base64, hash generator, UUID, regex tester and more. No signup, code never leaves your tab.
If you've ever stared at a single-line JSON response trying to find one missing bracket, you know why this section exists. Most developer utilities are either buried in heavy IDEs or on ad-covered sites that paste your code to a server.
Here the rule is simple: anything you paste stays in your tab. JSON formatting, Base64, hashing, UUIDs — all client-side. RSA generation uses your browser's own crypto (WebCrypto), which is actually more trustworthy than some random backend generating your private key.
Who are these code tools for?
Everyday jobs these tools handle well
Frontend/backend developers
Format API responses, encode tokens, generate UUIDs and hashes during debugging.
Students learning APIs
See JSON as a tree, understand nesting, validate before sending to a server.
DevOps & security
Generate RSA pairs for SSH/servers, verify hashes, test regex safely.
How to get it right the first time
3 simple steps
Paste the ugly version first
Don't pre-clean. Paste the minified JSON or messy code as-is — the formatter handles it.
Validate before you blame your code
Half of 'API not working' bugs are malformed JSON. Format + validate here first, then check your fetch logic.
Never paste production secrets
Even though these tools are local-only, build the habit: use test keys here, keep real API keys in env files.
Real situations where this helps
Taken from jobs people actually do
API returns one giant line
Paste into JSON Formatter → tree view. Expand only the 'data' node you're debugging instead of scrolling 2000 lines.
Need SSH keys for a new VPS
RSA Generator → 2048-bit → download PEM. Copy the public key to the server, keep the private key offline. Two minutes.
Verify a downloaded file
Generate SHA-256 of the file locally, compare with the hash on the official site. Mismatch means re-download — don't install it.
Mistakes people make (so you don't have to)
Quick things worth knowing before you start
Using a private key generated on an unknown site
If a server generated it, it could have kept a copy. Prefer in-browser generation (like here) or openssl locally for anything serious.
Minifying without keeping the original
Always keep the readable version. Debugging minified code directly wastes hours.
Testing regex on 2 examples and shipping
Test with empty strings, special characters, and Unicode names too. Regex breaks on real data, not demo data.
All code tools on DailyTool
2 free tools, no signup
- JSON Formatter
Format and validate JSON with syntax highlighting
- RSA Key Generator
Generate 2048/4096-bit RSA key pairs, extract public keys & test encryption
Frequently Asked Questions
Questions people actually ask about code tools