Free Developer Tools
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Fast, free & ad-light
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Everything runs in your browser
A growing collection of free, no-signup tools for developers — built to be genuinely useful and to respect your privacy. Nothing you paste is uploaded or stored; every tool runs entirely in your browser.
Format, minify & validate JSON. Explains errors in plain English, points to the exact spot, and suggests fixes.
Open tool →Convert Spring Boot application.properties to application.yml and back. Handles lists, profiles & comments — and repairs broken files with one click.
Open tool →Analyze a Spring Boot 2→3 or 3→4 upgrade before you run it. Flags javax→jakarta imports, renamed properties, starters, dialects & Security changes — and, unlike a blind find-and-replace, keeps the JDK packages you must not touch.
Open tool →Build, validate & explain cron for Spring @Scheduled (6 fields), Quartz and crontab. See the next run times in any time zone, fix "must consist of 6 fields" in one click, and convert between the three.
Open tool →Build the config that connects Claude Desktop, Claude Code, VS Code or Spring AI to MCP servers — each in the shape it actually accepts. Paste a broken one and find out why it fails.
Open tool →Convert between Unix epoch timestamps and human-readable dates, in any timezone.
Open tool →Encode text to Base64 or decode Base64 back to text, instantly in your browser.
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