Developer tools are the tiny jobs between the big ones: JSON that will not parse, a token to read, a color in the wrong format. On ToolPeko they run inside your browser, so API responses, tokens and config files never leave your machine. Every tool is free.
Every tool below runs in your browser, on your own device. Open one, finish the job, close the tab. Nothing you use here is uploaded or stored.
Paste messy JSON, get it neat and valid.
Check JSON and find the exact line that breaks it.
Squeeze JSON down to one tight line.
Open JSON as a tree you can fold and explore.
JSON rows turned into a CSV a spreadsheet can open.
A CSV file turned into clean JSON objects.
JSON rewritten as YAML for config files.
YAML config turned into JSON you can use in code.
Indent messy XML so its structure makes sense.
Beautify packed HTML into readable, nested lines.
Strip the spaces out of HTML to make it lighter.
CSS squeezed down for a faster page load.
One-line CSS spread back out so you can read it.
JavaScript packed tight for production.
Minified JavaScript opened back up, line by line.
Long SQL queries laid out so they can be read.
Turn plain text into Base64, ready to send or store.
Turn Base64 back into the text it carries.
Encode links safely or decode percent signs back.
Swap characters like < and & with their HTML codes.
Read the header and payload inside a JWT token.
MD5 and SHA hashes of any text, made in your browser.
Test a regex on your text and see every match marked.
Unix timestamps turned into dates you can read.
Read a cron schedule in plain words, with next runs.
Fresh random UUIDs, one or a whole batch.
Pick a color and get its HEX, RGB and HSL codes.
A HEX color code turned into RGB values.
RGB values turned into a HEX color code.
Half of debugging is small translation work. A response arrives as one long line, a token needs reading, a config file is in the wrong format. The tools are trivial. Sending your production data to a random server to use them is not. Everything on this page runs in your browser.
JSON, the daily bread: JSON Formatter takes messy JSON and makes it neat and valid. JSON Validator checks it and points at the line that breaks. JSON Minifier squeezes it back down, JSON Viewer opens it as a folding tree, and the converters move it around: JSON to CSV, CSV to JSON, JSON to YAML and YAML to JSON for config work.
Format and shrink code: XML Formatter, HTML Formatter and SQL Formatter lay tangled markup and queries out so they can be read. The minifiers pack for production, HTML Minifier, CSS Minifier and JS Minifier, and the beautifiers undo the packing when you inherit someone else’s code: CSS Beautifier and JS Beautifier.
Encode, decode, generate: Base64 Encode and Base64 Decode handle text in both directions. URL Encoder Decoder and HTML Encoder Decoder fix the other two encodings that break pages. JWT Decoder reads the header and payload inside a token, Hash Generator makes MD5 and SHA hashes, Regex Tester shows every match a pattern finds, Timestamp Converter turns Unix time into dates, Cron Parser explains a schedule in plain words, and UUID Generator makes fresh IDs one at a time or in a batch. Colors close the page: Color Picker, HEX to RGB and RGB to HEX.
| Your problem | Use this | Why it fits |
|---|---|---|
| An API sent back one giant unreadable line | JSON Formatter | Indented and valid, ready to read |
| My JSON fails and I cannot see where | JSON Validator | The exact breaking line is pointed out |
| I need to see what this token actually says | JWT Decoder | Header and payload as readable JSON |
| A link breaks because of spaces and symbols | URL Encoder Decoder | Encoded the way browsers expect |
| My regex matches too much, or nothing | Regex Tester | Every match marked on your own text |
| What date is 1735689600? | Timestamp Converter | Unix time as a date you can read |
| I inherited minified CSS and must change it | CSS Beautifier | Spread back out, rule by rule |
| The design gives colors in HEX, the code wants RGB | HEX to RGB | Same color, the format your code uses |
Every tool on this page runs in your browser tab. Your code, tokens and data never leave your machine. That is not a nicety here, it is the point: the JSON you most need to inspect is usually the JSON you least want on a stranger’s server, full of user records, keys and internal URLs. You can prove it by loading a tool, turning your internet off, and watching it keep working.
Straight talk on three things developers get wrong with tools like these:
A support engineer pastes a failing API response and finds the trailing comma in ten seconds. A junior developer decodes the token from a login bug instead of guessing at it. A designer and a developer stop arguing because the color is finally in both formats. None of these jobs needed an install, an account, or a quiet worry about where the data went.
Yes. Every tool on this page is free, with no paid tier and no sign-up. ToolPeko earns from ads on the site.
No. The tools run entirely in your browser. API responses, tokens and config files stay on your machine. Turn off your internet after the page loads and they still work.
Yes. It reports the line and position of the first problem, which is where JSON almost always breaks: a missing comma, a trailing comma, or an unclosed bracket just above it.
No. Base64 is encoding, not encryption. Anyone can decode it in seconds. Use it to carry data safely through systems, never to protect a secret.
It shows the header, the payload and the expiry in readable form. It does not verify the signature, because that needs the secret or public key on your server. Treat it as a reader, not a judge.
Once a tool page has loaded, yes. The work is done by your browser, so a dropped connection does not stop a format, encode or conversion mid-job.
SHA-256 for anything new. MD5 still serves for spotting accidental file changes, but it is too weak for passwords or security checks.
This is only one drawer of the toolbox. The rest work the same way: free, in your browser, with nothing uploaded.