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Dev Tools

JSON, regex, SQLite and 33 more developer tools · Free developer tools app for your browser

Dev Tools is a free set of 36 developer tools that run in your browser on a phone or computer, from a JSON formatter, regex tester and JWT decoder to a SQLite viewer and diff checker, with no account and nothing you paste uploaded.

Thirty-six developer tools in one fast app, all running in your browser so nothing you paste is ever uploaded. Format and validate JSON with the exact line of any mistake, a tree view and JSONPath; test a regular expression with every match highlighted and the pattern explained in plain English; decode a JWT and verify its signature; encode and decode Base64 and URLs; get MD5 and SHA hashes of text or files; generate UUID v4 and v7, ULIDs and NanoIDs; convert Unix timestamps; read cron expressions and their next runs; open a SQLite database, or CSV and JSON files as tables, and query them with SQL; diff two texts, or two Word or PDF files; turn CSV and YAML into JSON and JSON into TypeScript; format SQL, HTML, CSS and JavaScript; minify; make lorem ipsum; send HTTP requests and import curl commands and Postman collections; convert case, HTML entities and number bases; preview Markdown, format XML, sort and de-duplicate lines, escape strings, see text as hex, try HTML in a playground, look up HTTP status codes, read user agents and keycodes, and work out chmod, subnets, px to rem and aspect ratios. Free with no size limits, works offline.

Free to use. Optional one-time upgrade: Dev Tools Pro, $1.99 (no subscription), or every upgrade in every Yuzool app with Yuzool Plus, $19.99 once. Works on iPhone, Android, Mac and PC; add it to your Home Screen to open it like an app.

Quick answers about Dev Tools

Is it safe to paste JSON or a JWT into an online tool?
Only if the tool runs in your browser. Dev Tools formats JSON and decodes JWTs on your own device, sends nothing anywhere and works with your connection off once loaded, so API responses and tokens never leave your computer.
How do I find the error in my JSON?
Paste it into Dev Tools' JSON formatter: it gives the line and column of the first mistake with a plain reason, such as a trailing comma or a single-quoted key, and Show me jumps to it.
How can I open a SQLite database without installing anything?
Drop the .sqlite or .db file into Dev Tools' SQLite viewer: SQLite runs inside your browser, so you can browse the tables, run SQL and export results as CSV or JSON. CSV and JSON files open as tables too.
Is there a free regex tester that explains the pattern?
Yes. Dev Tools' regex tester highlights every match as you type, lists the capture groups, previews a replacement and explains each part of the pattern in plain English, using your browser's JavaScript regex engine.
How do I convert a Unix timestamp to a date?
Paste it into the Unix timestamp converter in Dev Tools: it reads seconds, milliseconds, microseconds or nanoseconds and shows the moment in UTC, your own time and any time zone. Today's 10-digit timestamps are seconds; 13 digits are milliseconds.
Can I compare two PDF or Word files for changes?
Yes, by their text. Dev Tools' diff checker reads .docx, .odt and PDF files in your browser and marks every added, removed and changed line, with the changed words inside each line. Scanned PDFs have no text to compare.
Does Dev Tools upload my data?
No, it all stays on your device, and it works offline.

Guide: How to decode a JWT safely, and check its signature

Also on Yuzool: JSON formatter and validator · Regex tester · JWT decoder · Base64 encode and decode · URL encode and decode · Hash generator · UUID generator · Unix timestamp converter · Cron expression explainer · Diff checker · SQLite viewer · CSV to JSON converter · YAML to JSON converter · JSON to TypeScript · SQL formatter · Code formatter · Minifier for HTML, CSS and JavaScript · Lorem ipsum generator · HTTP request tester · Case converter · HTML entities encoder and decoder · Number base converter · XML formatter and validator · Markdown preview · Sort lines and remove duplicates · String escape and unescape · Text to hex and binary · HTML playground · HTTP status codes · User agent parser · JavaScript keycode viewer · Chmod calculator · Subnet calculator · Px to rem converter · Aspect ratio calculator

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