Developer tools
Free online developer tools that run entirely in your browser. Format and validate JSON, encode and decode Base64, decode JWTs, generate hashes and UUIDs, and encode URLs without sending anything to a server. Fast, private, and free.
All developer tools
API Key Generator
Generate cryptographically random API keys and tokens in hex, base62, or base64url, with control over length, an optional prefix, and bulk output.
ASCII Table Reference
The full ASCII character set with decimal, hex, octal, binary, and HTML codes. Search by code, character, or name.
Atbash Cipher
Mirror the alphabet so A swaps with Z, B with Y, and so on. Atbash is its own inverse, so one field both encodes and decodes as you type.
Barcode Generator
Turn a product code, part number, or any text into a Code 128, EAN-13, UPC-A, Code 39, or ITF barcode and download it as an SVG or PNG.
Base32 Encoder and Decoder
Encode text to standard Base32 and decode Base32 back to text, following RFC 4648.
Base58 Encoder and Decoder
Encode text or hex to Base58 and decode Base58 back to bytes, with the Bitcoin, Ripple, and Flickr alphabets and optional Base58Check.
Base64 Encode & Decode
Encode text, files, and images to Base64, decode it back, and get a ready-to-use data URI.
Basic Auth Header Generator
Turn a username and password into an HTTP Basic Authorization header, with the raw token and a ready-to-copy curl or fetch snippet.
Caesar Cipher
Encode and decode Caesar cipher text with any shift, then brute force all 25 keys to crack it.
Chmod Calculator
Work out a Unix file permission number by toggling read, write, and execute for owner, group, and other, with setuid, setgid, and sticky bit support.
Coin Flip
Flip a virtual coin and watch the heads, tails, and streak tallies build up.
Common Port Numbers Reference
Search well-known TCP and UDP port numbers and copy the one you need.
CRC32 Checksum Calculator
Compute the IEEE 802.3 CRC-32 of text or a file, as 8-digit hex and an unsigned decimal integer.
Test Credit Card Number Generator
Generate fake, Luhn-valid card numbers with an expiry and CVV for testing payment forms. They are format-valid test values only: they cannot be charged and belong to no account.
Credit Card Number Validator
Check whether a card number passes the Luhn checksum and detect its network. Format checks only; nothing is charged, stored, or sent anywhere.
Crontab Expression Generator
Assemble a cron schedule field by field with visual pickers, then read it in plain English and preview the next run times.
CSP Header Generator
Build a Content-Security-Policy header directive by directive, with strict, moderate, and report-only presets and inline warnings when a choice weakens the policy.
CSS Beautifier & Minifier
Beautify minified CSS into readable rules, or strip comments and whitespace, with indent control and a size readout.
CSS Minifier
Strip comments and whitespace from CSS to shrink it, or beautify a minified stylesheet back into readable rules, with a size saved readout.
CSS Selector Tester
Paste an HTML fragment and a CSS selector to see exactly which elements match, with an optional highlighted view of the source.
CUID Generator
Generate collision-resistant CUIDs in bulk, in the standard or a shorter slug form.
cURL to Fetch Converter
Paste a curl command and get the equivalent JavaScript, with the method, headers, body, and basic auth carried across.
Data URI Generator
Turn any file, image, or SVG into a ready-to-paste data URI, with CSS and img snippets.
Dice Roller
Roll d4 to d100 dice with any count and a modifier, and see each die, the subtotal, and the total.
Docker Run to Compose Converter
Paste a docker run command and get the equivalent Compose service definition, with any flag it cannot map listed rather than dropped.
.dockerignore Generator
Build a .dockerignore from stack presets for Node, Python, Go, and more. Merge the patterns, drop duplicates, add your own lines, then copy or download the file.
.editorconfig Generator
Build a valid .editorconfig for your project. Set the indent style, size, line endings, charset, and whitespace rules, add per file overrides, then copy or download the file.
Email Address Validator
Check one address or a whole list for format problems, with a per-address reason and a suggested fix for common domain typos.
Env to JSON Converter
Convert a .env file of KEY=value lines to a JSON object, or turn a JSON object back into KEY=value lines, with quoted and multi-line values handled correctly.
File Hash & Checksum Tool
Compute a file MD5, SHA-1, SHA-256, and SHA-512 checksum, and verify it against an expected value.
.gitattributes Generator
Build a .gitattributes file from toggles: normalize line endings, force LF or CRLF for named extensions, mark binary types, track files with Git LFS, and exclude paths from language stats and archives.
.gitignore Generator
Build a clean .gitignore for your project from ready-made templates. Pick the languages, frameworks, build tools, editors, and operating systems you use, merge and dedupe overlapping patterns, add your own rules, then copy or download the file.
Hash Generator
Hash text or any file to MD5, SHA-1, SHA-256, and SHA-512, and verify a checksum.
HMAC Generator
Compute an HMAC of a message with your secret key using SHA-256, SHA-1, SHA-384, or SHA-512, in hex and Base64.
.htaccess Redirect Generator
Turn a list of old and new URLs into Apache redirect rules. Set each row to exact or pattern matching, force HTTPS, canonicalize www, then copy a ready .htaccess block wrapped in <IfModule mod_rewrite.c>.
HTML Entity Encoder
Encode text to HTML entities and decode entities back to plain text, both directions.
HTML Formatter & Beautifier
Beautify messy or minified HTML with indent, line wrap, and line break control.
HTML Minifier
Shrink HTML by removing comments and collapsing whitespace, while leaving preformatted text, inline scripts, and inline styles untouched. See the size saved.
HTML to JSX Converter
Paste an HTML snippet and get valid JSX. Class becomes className, for becomes htmlFor, inline styles become style objects, and void tags self-close.
HTTP Status Codes Reference
Search every HTTP status code, see what it means, and copy it with a click.
IP Subnet Calculator
Enter an IPv4 address in CIDR notation and see the network, broadcast, mask, host range, and host count.
JavaScript Formatter
Pretty-print minified or messy JavaScript with consistent indentation, spacing, and line breaks.
JavaScript Minifier
Shrink JavaScript by removing whitespace and comments and shortening local names, with a size saved readout.
JSON Diff Checker
Compare two JSON documents and see every added, removed, and changed value listed by its path.
JSON Escape and Unescape
Convert text to and from JSON string literals, with correct quote, backslash, and newline escaping.
JSON Formatter & Validator
Pretty-print, minify, or explore JSON as a collapsible tree, with syntax errors shown inline.
JSON Minifier
Minify JSON to the smallest single line, with original vs minified byte size and the percentage saved.
JSON Path Finder
List every value in a JSON document with its exact access path, then filter to find the one you need.
JSON Schema Generator
Paste a JSON sample and get a JSON Schema, with property types, array items, required fields, and string formats inferred for you.
JSON Key Sorter
Alphabetise the keys of any JSON document at every level of nesting, then pretty-print the result.
JSON to Go Struct
Paste JSON and get typed Go structs, with nested types, slices, json tags, pointers, and omitempty handled for you.
JSON to Python
Paste JSON and get Python classes inferred from its shape, as dataclasses, typed dictionaries, or plain dictionary access.
JSON to SQL Converter
Paste a JSON array of objects and get SQL INSERT statements, with correct quoting, typed columns, and an optional CREATE TABLE.
JSON to TypeScript
Paste JSON and get typed TypeScript interfaces, with nested objects, arrays, optional fields, and null handled for you.
JWT Decoder
Decode a JSON Web Token and optionally verify its signature, right in your browser.
JWT Generator (Signer)
Build and sign a JSON Web Token from a header, payload, and secret, right in your browser.
MAC Address Generator
Generate random 48-bit MAC addresses in colon, hyphen, Cisco dot, or plain format, with an optional vendor prefix, locally administered and unicast control, and bulk output.
Markdown Table Generator
Build a Markdown table in a visual grid. Set rows and columns, type cell values, pick per-column alignment, and copy the generated Markdown.
MD5 Hash Generator
Compute the MD5 checksum of text or a file. Copy it as hex or Base64.
Meta Tag Generator
Build the search and social meta tags for any web page. Fill in the title, description, canonical URL, Open Graph, and Twitter fields, then copy a ready block of HTML with a live search snippet and social card preview.
MIME Type Lookup
Type a file extension to get its MIME type, or paste a MIME type to see which extensions use it.
Mock Data Generator
Build a schema and generate fake records as JSON, CSV, SQL inserts, or NDJSON. Add a seed to get the same data every time.
Nano ID Generator
Generate short, URL-safe unique IDs with adjustable length, count, and alphabet.
Nginx Redirect Generator
Paste a list of old paths and new paths and get an nginx server block with matching return directives, or redirect an entire domain in one go.
MongoDB ObjectID Generator
Generate valid MongoDB ObjectIDs in bulk and decode any ID back to its creation time.
Passphrase Generator
Create a memorable, strong passphrase from random common words, with control over word count, separator, capitals, and an optional number.
Password Generator
Create strong random passwords or memorable passphrases, with control over length, characters, word count, and bulk output.
Password Strength Checker
See how strong a password is, with an entropy estimate in bits, an approximate offline crack time, a 5-level meter, and specific tips to make it harder to guess.
Punycode Converter
Encode internationalized domains to xn-- ASCII and decode them back to Unicode.
Query String Parser
Paste a URL or query string, edit every parameter in a decoded table, and copy the rebuilt query string and full URL.
Random Email Generator
Generate correctly formed but undeliverable email addresses for form testing and seed data.
Random Number Generator
Draw random whole or decimal numbers from any range, with no-repeat batches and sorting.
Random String Generator
Generate random strings for IDs, keys, tokens, and test data, with control over length, character sets, and how many you make at once.
Regex Cheatsheet
Searchable regex syntax reference with plain meanings, examples, and copyable common patterns.
Regex Tester
Test regular expressions live against sample text, with match highlighting, capture groups, find and replace, and all six flags.
robots.txt Generator
Build a valid robots.txt with grouped crawler rules, crawl-delay, and a sitemap line.
ROT13 Encoder
Apply the classic ROT13 cipher or any ROT-N shift from 1 to 25. Letters rotate, everything else stays put, and you get the encoded and decoded text at once.
Semantic Version Calculator
Compare two versions by semantic-versioning precedence, work out the next release with a bump, and check a version against a range.
SHA-1 Hash Generator
Hash any text or file to its SHA-1 digest as you type, then copy it as lowercase hex, uppercase hex, or Base64.
SHA-256 Hash Generator
Turn any text into its SHA-256 hash as you type, with SHA-1 and SHA-512 alongside and a one-tap uppercase switch.
SHA-512 Hash Generator
Hash any text or file with SHA-512 as you go, switch to SHA-384, and copy the digest as lowercase hex, uppercase hex, or Base64.
XML Sitemap Generator
Turn a list of page URLs into a valid sitemap.xml. Add lastmod, changefreq, and priority, then copy or download the file.
SQL Formatter & Beautifier
Beautify SQL queries with dialect-aware formatting, keyword casing, and indent control.
SQL Minifier
Collapse a SQL query onto a single line and strip comments, while keeping strings, quoted identifiers, and semicolons intact, with a character count saved readout.
String Escape / Unescape
Escape or unescape a string using the rules of JavaScript, JSON, Java, Python, SQL, CSV, and shell.
Text to Octal Converter
Convert text to octal codes and octal back to text, live, in both directions.
ULID Generator
Generate lexicographically sortable ULIDs in bulk, in upper or lowercase.
URL Encode & Decode
Percent-encode text for URLs and decode it back, both directions.
URL Parser
Paste a URL and see every part broken out, with a decoded table of its query parameters.
User Agent Parser
Read any user agent string as browser, operating system, device type, and rendering engine, starting with your own.
Username Generator
Create usernames and handles in a few styles, with control over separators, numbers, length, and bulk output.
UTM Builder
Build campaign tracking links with properly encoded UTM parameters.
UUID Generator
Generate version 4 and version 7 UUIDs in bulk, with case and format options.
UUID v5 Generator
Generate deterministic name-based UUIDs from a namespace and a name. Supports version 5 and version 3, single values or whole batches.
UUID Validator
Check one identifier or a whole list for valid UUID format, with the version, variant, and embedded timestamp for each valid one.
Vigenere Cipher
Encode and decode Vigenere cipher text with a keyword, preserving case and punctuation, and watch the running key line up with each letter.
XML Formatter & Validator
Pretty-print, minify, and validate XML, with the parse error shown inline.
XML Minifier
Remove the whitespace between tags to shrink an XML document, with a size saved readout. Attribute values, CDATA, and preserved content are left untouched.
XPath Tester
Run an XPath expression against XML or HTML and see every matching node, with its name, text, and full markup.
YAML Formatter & Validator
Validate a YAML document and reformat it in a clean, canonical form, with sorted keys, quote and indent control, and errors that point at the exact line.
Create ZIP File
Bundle any set of files into a single .zip archive, right in your browser.
Frequently asked questions
- Is my data sent to a server?
- No. JSON formatting, Base64 conversion, JWT decoding, hashing, UUID generation, and URL encoding all run locally in your browser. Tokens, payloads, and secrets never leave your device.
- Which developer tools are available?
- A JSON formatter and validator, Base64 encode and decode, a JWT decoder, a hash generator, a UUID generator, and URL encode and decode, with more added over time.
- Is it safe to decode a JWT or hash sensitive values here?
- Yes. The JWT decoder only reads the token client-side to show its header and payload, and never verifies or stores it remotely. Hashing also runs entirely on your device, so nothing is transmitted.
- What hash algorithms and UUID versions are supported?
- The hash generator covers common algorithms such as MD5, SHA-1, and SHA-256, and the UUID generator produces standard random identifiers ready to copy.
- Are the developer tools free?
- Yes. Every developer tool is free to use, with no account, no sign-up, and no rate limits.