These tools are for developers, sysadmins, QA testers and technical marketers who handle structured data, code snippets and URLs every day. Use them when you need to check a payload, reshape a file or build a config value without opening an IDE or installing a package.
They all work the same way: the processing happens in JavaScript inside your browser tab, and nothing you paste is uploaded. The JSON Formatter uses the browser's own parser and the Hash Generator uses the Web Crypto API, so results match what your code would produce. Even so, rotate any real secret that has been pasted somewhere it shouldn't be.
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All developer tools
JSON Formatter
Validate and pretty-print JSON.
Base64 Encode / Decode
Convert text to and from Base64.
Hash Generator
Generate SHA-1, SHA-256, SHA-512 hashes.
UUID Generator
Generate RFC-4122 v4 UUIDs.
URL Encode / Decode
Percent-encode strings and URLs.
Regex Tester
Test regex patterns with live highlighting.
Markdown Previewer
Live-render Markdown as you type.
CSS Minifier
Strip whitespace and comments from CSS.
JS Minifier
Light cleanup for smaller JS files.
Unix Timestamp Converter
Convert Unix epoch time to a date, and back.
JWT Decoder
Decode a JSON Web Token's claims.
Cron Expression Generator
Build a cron schedule visually.
Binary Translator
Translate text to binary and hex, and back.
CSV to JSON
Convert CSV or spreadsheet rows into JSON.
JSON Diff
Compare two JSON documents by path.
Markdown Table Generator
Turn CSV or spreadsheet cells into a Markdown table.
JSON to CSV
Convert JSON to CSV and flatten nested objects.
YAML to JSON
Convert YAML to JSON and JSON to YAML.
PX to REM Converter
Convert px to rem and back, with a 16px chart.
Subnet Calculator
IPv4 CIDR, subnet mask, hosts and ranges.
XML Formatter
Pretty print, minify and check XML.
HTML Formatter
Beautify or minify HTML code.
SQL Formatter
Format SQL queries for 14 dialects.
Screen Resolution Checker
See your screen, viewport and pixel ratio.
Keyboard Tester
Test every key and key rollover online.
Mic Test
Check your microphone with a live meter.
UTM Builder
Tag campaign links for Google Analytics 4.
Chmod Calculator
Octal, symbolic and umask permissions.
JSON to XML Converter
Convert JSON to XML and XML to JSON.
CSS Grid Generator
Build grid layouts with CSS and Tailwind output.
AES Encryption
Encrypt and decrypt text with AES using a passphrase.
Docker Run to Compose
Convert a docker run command to docker-compose.yml.
RSA Key Generator
Generate an RSA key pair in PEM format.
ULID Generator
Sortable unique IDs, batch generate and decode.
TOTP Generator
Get 2FA codes from a secret and verify codes.
URL Parser
Split a URL into parts and edit its query.
User Agent Parser
See the browser, OS and device behind a user agent.
How to choose
Many of these tools look alike because they all take pasted text. The useful question is what you need done to it: made readable, checked, turned into something else, or built from scratch.
Formatting: change the layout, not the meaning
The JSON Formatter, XML Formatter, HTML Formatter and SQL Formatter re-indent code so you can read it. Going the other way, the CSS Minifier and JS Minifier strip comments and whitespace. The JS Minifier does not rename variables, so for a production bundle a build-tool minifier such as Terser will produce a smaller file.
Validating: only some formatters check your code
The JSON Formatter parses with JSON.parse() and reports the error if parsing fails. The XML Formatter checks that a document is well-formed and gives a line and column, but it does not validate against an XSD schema. YAML to JSON also reports parse errors by line and column. The SQL and HTML formatters do not validate at all: a broken query or an unclosed tag is simply re-indented. The Regex Tester checks a JavaScript pattern against your sample text, and the JWT Decoder reads a token's claims without verifying its signature.
Converting: same data, different shape
For data formats, use CSV to JSON, JSON to CSV, YAML to JSON or JSON to XML. Expect some loss: JSON to CSV flattens nested objects into dot keys, and YAML comments and anchors have no JSON equivalent. For encodings and units, use Base64, URL Encode/Decode, the Binary Translator, the Timestamp Converter or PX to REM.
Building and comparing
Some tools write a value for you: the Cron Generator, UTM Builder, CSS Grid Generator, Markdown Table Generator, Chmod Calculator, Subnet Calculator and UUID Generator. To compare, use JSON Diff for two documents or the Hash Generator to check a checksum. The Screen Resolution Checker, Keyboard Tester and Mic Test check your hardware instead of your code.
Matching the tool to the data in front of you
Most debugging starts with a string you don't recognize. Its shape usually tells you which tool to open:
- Starts with
{or[: it's JSON. Validate it with the JSON Formatter, or compare two versions with JSON Diff. - Three dot-separated chunks starting with
eyJ: almost certainly a JWT, because Base64-encoded JSON objects begin that way. Open it in the JWT Decoder. Remember that decoding doesn't verify the signature. - Letters, digits,
+,/, maybe=padding at the end: likely Base64. Use Base64 Encode/Decode. - Lots of
%20and%3D: percent-encoding. Use URL Encode/Decode. - A 10- or 13-digit number: a Unix timestamp in seconds or milliseconds. Use the Timestamp Converter.
- 32 hex digits in 8-4-4-4-12 groups: a UUID. The UUID Generator creates new ones.
- A fixed-length hex string: often a hash. SHA-256 is 64 hex characters and SHA-1 is 40. Recompute it with the Hash Generator to compare.
Guides
JSON Formatting Best Practices for Developers
Why pretty-printed JSON matters and how to catch the syntax errors that break parsers.
GUIDEJSON vs XML: Key Differences and When to Use Each
The same data in both formats, their data types and schemas, and what breaks when you convert.
GUIDEUnix Time Explained: Why Computers Count From 1970
Epoch time, the seconds-vs-milliseconds trap and the Year 2038 problem.
GUIDEUUID vs. Random Number: Which Generator Do You Actually Need?
When you need a unique identifier and when a random number is enough.
GUIDEchmod 777, 755 and 644 Explained: Linux File Permissions
How each chmod digit adds up from read, write and execute, and why 777 is risky.
GUIDECSS Grid vs Flexbox: When to Use Each (With Examples)
One-dimensional vs two-dimensional layout, with a checklist for picking each.
GUIDE10 Browser-Based Tools That Save Developers Time
A roundup of small browser utilities worth bookmarking for daily work.
Frequently asked questions
No. All parsing, hashing, and encoding happens locally in your browser — nothing is transmitted or logged.
Yes, it uses your browser's native JSON.parse, so error messages match exactly what your own code will see.
Yes — hashing uses the Web Crypto API (SubtleCrypto), the same engine built into modern browsers, supporting SHA-1, SHA-256, and SHA-512.
The JSON Formatter, XML Formatter and YAML to JSON converter report parse errors. The SQL Formatter and HTML Formatter only re-indent code, so a broken query or an unclosed tag is not flagged.
No. It decodes the header and payload so you can read the claims, and its expiry status only compares exp with your device's clock. Checking the signature needs the signing key, which belongs on your server.