Developer Tools
130 free tools
Essential developer utilities - formatters, validators, encoders, generators, and debugging tools for web developers.
Developer tools handle the everyday text-transformation, encoding, validation, and generation tasks that slow down coding workflows. Rather than writing one-off scripts or switching between multiple browser tabs, you can access every utility — JSON formatter, regex tester, Base64 encoder, JWT decoder, hash generator — in one place.
All tools run client-side in JavaScript, making them fast and private. There is no upload to a server; paste your code, click process, and get your result. Our developer tools are used by full-stack developers, backend engineers, DevOps professionals, and QA engineers daily.
Code Formatters20
HTML Prettifier
Reformat HTML with proper nested indentation based on actual tag depth, handling void elements like <br> and <img> correctly.
CSS Prettifier
Reformat minified or messy CSS with a newline after each rule, selector, and declaration for readability.
SCSS Formatter
Clean up whitespace and blank lines in SCSS/Sass code — a light touch-up, not a full SCSS-aware reformatter.
LESS Formatter
Clean up whitespace and blank lines in LESS stylesheet code — a light touch-up, not a full LESS-aware reformatter.
JSON5 Formatter
Strip comments and trailing commas from JSON5 input, then pretty-print it as standard indented JSON.
GraphQL Formatter
Clean up whitespace and blank lines in GraphQL queries or schemas — a light touch-up, not a full GraphQL-aware reformatter.
Markdown Formatter
Clean up common Markdown formatting issues — heading spacing, extra bold markers, and blank-line runs.
YAML Formatter
Reindent YAML based on key and list-item structure, applying consistent 2-space nesting.
TOML Formatter
Attempt to pretty-print TOML-like config data — works well for JSON-shaped input, falls back to basic brace cleanup for real TOML syntax.
Dockerfile Formatter
Clean up whitespace and blank lines in a Dockerfile — a light touch-up, not a Dockerfile-aware reformatter.
NGINX Config Formatter
Clean up whitespace and blank lines in an NGINX config file — a light touch-up, not an NGINX-aware reformatter.
SQL Prettifier
Reformat SQL by inserting a line break before each major keyword (SELECT, FROM, WHERE, JOIN, etc.).
NoSQL Formatter
Pretty-print MongoDB/NoSQL query documents — works well for JSON-shaped queries, falls back to basic brace cleanup otherwise.
Bash Script Formatter
Clean up whitespace and blank lines in a Bash/shell script — a light touch-up, not a shell-aware reformatter.
PowerShell Formatter
Clean up whitespace and blank lines in a PowerShell script — a light touch-up, not a PowerShell-aware reformatter.
Perl Formatter
Clean up whitespace and blank lines in Perl code — a light touch-up, not a Perl-aware reformatter.
Lua Formatter
Clean up whitespace and blank lines in Lua code — a light touch-up, not a Lua-aware reformatter.
Kotlin Formatter
Clean up whitespace and blank lines in Kotlin code — a light touch-up, not a Kotlin-aware reformatter.
Dart Formatter
Clean up whitespace and blank lines in Dart/Flutter code — a light touch-up, not a Dart-aware reformatter.
R Code Formatter
Clean up whitespace and blank lines in R code — a light touch-up, not an R-aware reformatter.
Code Validators20
JSON Validator
Validate JSON syntax in your browser using the same parser JavaScript itself uses, with the exact error message if parsing fails.
XML Validator
Validate XML well-formedness using the browser's built-in XML parser, reporting the root element and child count on success.
HTML Validator
Validate HTML5 markup for errors, accessibility issues, and best-practice warnings — instantly in your browser.
CSS Validator
Run basic heuristic checks on CSS — mismatched braces, likely missing semicolons, and empty rule blocks — not a full W3C validation.
JavaScript Linter
Get a pointer to real JavaScript linting tools — this page does not actually parse or lint your code.
YAML Validator
Run basic heuristic checks on YAML — flags tab characters (invalid in YAML) and possible key/value formatting issues.
robots.txt Validator
Check a robots.txt file for a User-agent directive and confirm every non-comment line has the expected colon syntax.
Sitemap Validator
Check whether an XML sitemap is well-formed and count the URLs it contains, using the browser XML parser.
JSON Schema Validator
Validate JSON data against a simplified schema — checks required fields are present and basic property types match.
CSV Validator
Check that every row in a CSV file has the same number of columns as the header row.
Markdown Validator
Check Markdown for a couple of common issues: multiple or missing H1 headings, and empty link syntax.
Regular Expression Validator
Check whether a regular expression pattern compiles without a syntax error, using the JavaScript regex engine.
Cron Expression Validator
Check that a cron expression has the correct 5-field structure and that each field uses recognized cron syntax.
JWT Validator
Decode a JWT and check its structure, algorithm, and expiry claim — without verifying the cryptographic signature.
API Response Validator
Get a pointer to real API testing tools — this page does not actually validate or parse your API response.
SQL Syntax Checker
Reformat SQL with keyword line breaks, plus one basic structural check: flagging a SELECT with no matching FROM.
XPath Tester
Test and debug XPath expressions against any XML document instantly in your browser.
JSONPath Tester
View a JSONPath syntax reference/cheatsheet — this page does not actually run your JSONPath expression against data.
Dockerfile Linter
Get a pointer to hadolint, the real Dockerfile linter — this page does not actually lint your Dockerfile.
Gitignore Checker
Check a .gitignore file for duplicate patterns and compare it against a checklist of 6 common entries.
Encoders & Decoders20
Base64 Encoder
Encode any text into Base64 using the browser-native btoa() function, with full Unicode/UTF-8 support.
Base64 Decoder
Decode Base64 back to readable text using the browser-native atob() function, with full Unicode/UTF-8 support.
URL Encoder
Percent-encode text for safe use in URLs, or decode it back, using the native encodeURIComponent/decodeURIComponent functions.
URL Decoder
Decode percent-encoded URL text back to its original characters using the native decodeURIComponent function.
HTML Entity Encoder
Convert special characters (<, >, &, quotes) into their HTML entity equivalents using the browser DOM, guaranteeing correct escaping.
HTML Entity Decoder
Convert HTML entities back to their original characters using the browser DOM, handling both named and numeric entities correctly.
JWT Decoder
Decode a JWT header and payload to readable JSON — a pure decode with no expiry or signature checking.
Hex Encoder
Convert text into its hexadecimal character-code representation, one byte per character.
Hex Decoder
Convert space-separated hexadecimal character codes back to text.
Binary Encoder
Convert text into 8-bit binary character codes, one byte per character, space-separated.
Binary Decoder
Convert space-separated binary character codes back to text.
Unicode Escaper
Escape non-ASCII characters into \uXXXX Unicode escape sequences, leaving standard ASCII characters untouched.
Unicode Unescaper
Convert \uXXXX Unicode escape sequences back into their original characters.
Punycode Converter
Convert internationalized domain name labels between Unicode and their ASCII-compatible Punycode form (the real xn-- encoding browsers use).
Quoted Printable Encoder
Encode text into Quoted-Printable format, escaping non-printable and high-bit characters as =XX hex codes with 76-character line wrapping.
Quoted Printable Decoder
Decode Quoted-Printable (=XX hex codes and soft line breaks) back into the original text.
ROT13 Encoder
Apply the ROT13 letter-substitution cipher — a fixed 13-position shift that is its own inverse.
ROT13 Decoder
Decode ROT13-encoded text — since ROT13 is self-inverse, this runs the exact same transformation as the ROT13 Encoder.
Caesar Cipher
Shift letters through the alphabet by a custom amount you choose, generalizing ROT13 to any shift value.
URL Safe Base64
Encode/decode Base64 using the URL-safe alphabet (- and _ instead of + and /), with padding removed — the format used in JWTs and URL query parameters.
Generators30
UUID Generator v4
Generate a random RFC 4122 version 4 UUID with the version and variant bits set correctly.
UUID Generator v1
Generate a real RFC 4122 version 1 (time-based) UUID, encoding the current timestamp plus a randomly-generated node identifier.
NanoID Generator
Generate a cryptographically random, URL-friendly ID using the same 21-character length and default alphabet as the popular nanoid library.
ULID Generator
Generate a real, spec-compliant ULID — a 26-character, lexicographically sortable ID with a Crockford base32-encoded timestamp and random suffix.
CUID Generator
Generate a CUID-style ID — a 'c' prefix, base36 timestamp, and cryptographically random suffix — a simplified approximation, not the exact CUID2 reference algorithm.
Snowflake ID Generator
Generate a Twitter Snowflake-format ID — a 64-bit integer combining a timestamp, fixed machine ID bits, and a random sequence number.
MD5 Hash Generator
Compute the MD5 hash of text using a pure-JavaScript RFC 1321 implementation (the Web Crypto API does not support MD5).
SHA-1 Hash Generator
Compute the SHA-1 hash of text using the browser-native Web Crypto API.
SHA-256 Hash Generator
Compute the SHA-256 hash of text using the browser-native Web Crypto API — the current standard for general-purpose cryptographic hashing.
SHA-512 Hash Generator
Compute the SHA-512 hash of text using the browser-native Web Crypto API.
SHA-3 Hash Generator
Get a SHA-256 fallback, not a real SHA-3 hash — the Web Crypto API does not support SHA-3/Keccak, and no library is included for it.
RIPEMD-160 Generator
Compute a real RIPEMD-160 hash using a pure-JavaScript implementation, verified against the official RFC test vectors.
HMAC Generator
Compute a real HMAC (keyed-hash message authentication code) using SHA-1, SHA-256, SHA-384, or SHA-512, via the Web Crypto API.
Checksum Calculator
Compute three real checksums at once — CRC32, MD5, and SHA-256 — for the same input text.
CRON Expression Generator
Build a real cron expression from 5 comma-separated fields (minute, hour, day, month, weekday), with a plain-English schedule description.
.htaccess Generator
Get a ready-to-use Apache .htaccess template with an HTTPS redirect rule and static-asset cache headers.
nginx.conf Generator
Generate a real NGINX server block template for your domain, with an HTTP-to-HTTPS redirect and a basic SSL server config.
Docker Compose Generator
Generate a docker-compose.yml template with a named app service and a PostgreSQL database service.
Git Command Generator
View a quick-reference list of common Git commands — a static cheatsheet, not commands generated from your specific situation.
Regex Generator
View a reference sheet of common regex patterns (email, URL, phone, date, IPv4, hex color) — a static cheatsheet, not a pattern generated from your description.
API Key Generator
Generate a cryptographically random hex string of a length you choose, suitable as an API key or secret.
Token Generator
Generate a cryptographically random hex string of a length you choose, suitable as a general-purpose secure token.
Nonce Generator
Generate a cryptographically random hex string suitable as a one-time-use cryptographic nonce.
Private Key Generator
Generate a real RSA-2048 or ECDSA P-256 key pair (PEM-encoded) directly in your browser using the Web Crypto API.
CSR Generator
Get the exact OpenSSL command and step-by-step instructions to generate a real Certificate Signing Request — this tool does not generate a CSR file itself.
Password Hash Generator
Compute a real PBKDF2-SHA256 password hash with 100,000 iterations — a genuine key-derivation function suitable for password storage, not a bare fast hash.
EAN/Barcode Generator
Generate a valid EAN-13 barcode number with a correctly computed check digit, plus links to real barcode-image renderers.
IBAN Generator
Generate a fake, clearly-labeled sample IBAN for UI mockups or testing — not a real, validatable bank account number.
Credit Card Generator
Generate Luhn-valid test credit card numbers for development and testing — not real, usable cards.
Lorem Picsum Generator
Generate a real, working placeholder image URL from the Lorem Picsum service, at whatever width and height you specify.
Debugging Tools20
Regex Tester
Test a regex pattern against sample text and see every match, using the real JavaScript regex engine.
Regex Debugger
Test a regex against sample text and see each match with its index position and any named/numbered capture groups.
Regex Replace
Run a real find-and-replace on text using a regex pattern and replacement string.
Regex Split
Split text into parts using a regex pattern as the delimiter, and see each resulting piece.
Regex Reference
View a reference sheet of common regex patterns and syntax basics — the same static content as the Regex Generator tool.
API Tester
Get a pointer to real API testing tools — this page does not actually send requests or test an API.
cURL Generator
Build a real, working curl command from a URL, HTTP method, and request body you specify.
cURL to HTTP
Parse a real curl command into its equivalent raw HTTP request format (method, path, headers, body).
HTTP Status Code Checker
Get a pointer to a real HTTP status checker — this page cannot reliably fetch the live status code of an arbitrary URL from your browser.
SSL Certificate Checker
Get a pointer to a real SSL/TLS certificate checker — this page cannot inspect a site's certificate details from your browser.
DNS Lookup
Get a pointer to a real DNS lookup tool — this page cannot perform DNS queries from your browser.
Whois Lookup
Get a pointer to a real WHOIS lookup tool — this page cannot query WHOIS registries from your browser.
IP Address Lookup
Get a pointer to a real IP lookup tool — this page cannot determine your public IP or geolocate an IP from your browser.
Port Scanner
Get a pointer to a real port scanning tool — this page cannot scan network ports from your browser.
HTTP Header Analyzer
Get a pointer to a real HTTP header analysis tool — this page cannot fetch and inspect response headers from an arbitrary URL.
Website Speed Test
Get a pointer to a real website speed testing tool — this page cannot measure a site's actual load performance from your browser.
Ping Test
Get a pointer to a real ping tool — this page cannot send ICMP ping packets from your browser.
Traceroute Tool
Get a pointer to a real traceroute tool — this page cannot trace network routes from your browser.
MIME Type Checker
Get a quick file-extension-based MIME type reference — this page cannot inspect a real file's actual content-type from your browser.
User Agent Parser
Parse a User-Agent string into browser name/version, operating system, and device type using real pattern matching.
CSS Tools20
CSS Minifier
A developer-tools-side CSS minifier — strips comments, collapses whitespace, and trims spacing around punctuation, part of ToolHive's CSS/SCSS/LESS toolset alongside the beautifier and preprocessor converters.
CSS Beautifier
Reformat minified or messy CSS with a newline after each rule, selector, and declaration — the same logic as the CSS Prettifier tool.
CSS to SASS
Get a lightly restructured starting point for SCSS conversion — not a real CSS-to-SCSS transpiler with nesting or variable extraction.
SASS to CSS
Get a basic structural cleanup of SASS/SCSS — not a real Sass compiler. Variables and nesting are not resolved.
CSS to Less
Get a lightly restructured starting point for LESS conversion — not a real CSS-to-LESS transpiler with nesting or variable extraction.
Less to CSS
Get a basic structural cleanup of LESS — not a real LESS compiler. Variables and nesting are not resolved.
CSS to Stylus
Get a lightly restructured starting point for Stylus conversion — not a real CSS-to-Stylus transpiler with nesting or variable extraction.
Stylus to CSS
Get a basic structural cleanup of Stylus — not a real Stylus compiler. Variables and nesting are not resolved.
CSS Gradient Generator
Build a real, working linear-gradient() CSS value from your comma-separated colors and angle.
Box Shadow Generator
Build a real, working box-shadow CSS value from your horizontal/vertical offset, blur, spread, and color.
Border Radius Generator
Build a real border-radius CSS declaration — a single value applied uniformly, plus the equivalent per-corner syntax.
Flexbox Generator
Build a real, complete set of flexbox container CSS properties from your direction, justify, align, and wrap choices.
Grid Layout Generator
Build real CSS Grid container properties from your column count, row template, and gap.
CSS Animation Generator
Build a real, working @keyframes fade-in animation with the name, duration, and easing you specify.
CSS Transform Generator
Build a real CSS transform declaration combining rotate, scale, and translate values you specify.
CSS Filter Generator
Build a real CSS filter declaration combining blur, brightness, contrast, and saturate values you specify.
CSS Triangle Generator
Build a real, working CSS-only triangle using the border trick, in your chosen direction, size, and color.
CSS Clip Path Generator
Get a working clip-path CSS value for one of 4 preset shapes — circle, ellipse, polygon (triangle), or rounded inset.
CSS Variables Extractor
Extract every real CSS custom property (--variable) from pasted CSS and list them in a clean :root block.
CSS Specificity Calculator
Calculate the real CSS specificity of a selector — ID count, class/attribute/pseudo-class count, and element count — using genuine pattern parsing.