Free Developer Utility Tools
Fast, free, no sign-up. Every tool runs entirely in your browser — nothing you paste here ever leaves your machine.
- 100% client-side
- no sign-up
- no uploads
- instant results
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JSON Formatter
Pretty-print, validate, and minify JSON with syntax highlighting and clear error messages.
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JSONPath Tester
Query and filter JSON with JSONPath. Every match shows the exact path it was found at.
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Regex Tester
Test regular expressions with live match highlighting, capture groups, and common presets.
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UUID Generator
Generate cryptographically secure UUID v4 identifiers, one at a time or in batches.
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Base64 Encoder / Decoder
Encode text to Base64 and decode it back, with full UTF-8 support for any language.
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Cron Parser
Translate cron expressions into plain English and preview the next scheduled run times.
Guides
Reference material for the things that waste an afternoon.
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Every
JSON.parseError ExplainedWhat each message actually means across Chrome, Firefox, Safari and Node — plus the two silent failures that are not errors at all.
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JSONPath Cheatsheet
Every operator with worked examples, and the seven places implementations disagree with RFC 9535.
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Base64: The Parts That Bite
Why
btoathrows on emoji, how base64url differs, and why Node decodes invalid input silently.
From the blog
Build notes and arguments. All posts →
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21 September 2026security
Where Developer Data Actually Leaks
Production data rarely escapes through a breach. It escapes through pastebins, online formatters, AI chat windows, screenshots and git history.
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21 September 2026opinion
Client-Side Tools Are a Security Decision
Pasting an API response into an online formatter is a data disclosure, not a convenience — and nothing in the interface tells you so.