Free Online Developer Tools - 115 Utilities for Web Developers
WebDevUtility is a set of 115 small tools for the jobs that interrupt real work: turning a JSON payload into a Go struct, decoding a token to see why an API rejected it, finding the one line where two config files differ, or shrinking an SVG icon exported from Figma.
Almost every tool runs in your browser tab with JavaScript, so nothing you paste is uploaded, logged or stored. You can put an API key, a production config or a customer export in the box, and it stays on your machine. Only the five network tools (DNS, WHOIS, redirect, uptime and IP checks) call our API, as the privacy policy explains.
There is no account or paid tier. Each tool also comes with a short guide that shows the equivalent code, usually in JavaScript, PHP and Python, for when the conversion belongs in your own codebase instead of a browser tab.
No tool matches that. Try a format name like json, csv or sql.
Latest guides
Unix Timestamp to Date in JavaScript, PHP, Python and MySQL
Convert Unix timestamps to dates in JavaScript, PHP, Python, MySQL and PostgreSQL: seconds vs ms, time zones, DST and the 2038 limit.
SHA-256 vs HMAC-SHA256: Differences and Code Examples
SHA-256 hashes a message; HMAC-SHA256 adds a secret key. When to use each, why neither suits passwords, and how to verify both.
Fix JSON.parse Unexpected Token Errors: Every Cause
Every JSON.parse SyntaxError and its fix: unexpected token <, single quotes, trailing commas, comments, end of input, BOM and NaN.
PHP Array to JSON: json_encode Flags Explained
How json_encode picks an object or array, what each flag changes, where floats and depth go wrong, and why it returns false silently.
Data Converters
JSON to PHP Array
Convert JSON to a PHP array in short [] syntax, ready to paste.
JSON to CSV
Convert a JSON array to CSV with the delimiter of your choice.
JSON to JavaScript
Convert JSON to a JavaScript object literal with unquoted keys.
JSON to YAML
Convert JSON to YAML for Kubernetes, Compose and CI config files.
JSON to Excel (XLSX)
Export a JSON array to an Excel .xlsx workbook.
JSON to XML
Convert JSON to XML, with arrays as repeated elements.
XML to JSON
Convert XML to JSON, keeping attributes and repeated elements.
CSV to JSON
Convert CSV to a JSON array of objects, with the header row as keys.
CSV to PHP Array
Convert CSV to a PHP array keyed by the header row.
CSV to JavaScript
Convert CSV to a JavaScript array of objects or arrays.
YAML to JSON
Convert YAML to JSON, with anchors and aliases resolved.
PHP Array to JSON
Convert PHP array() or [] literals to JSON without running PHP.
PHP Array to CSV
Convert a PHP array of rows to CSV for Excel or Google Sheets.
JSON to TypeScript
Generate TypeScript interfaces from a JSON sample.
JSON to Go Struct
Generate Go structs with json tags from a JSON sample.
JSON to Python Dataclass
Generate Python dataclasses, TypedDicts or Pydantic models from JSON.
JSON Schema Generator
Generate a JSON Schema from sample JSON, with formats and a required list.
CSV to SQL INSERT
Turn CSV rows into SQL INSERT statements, with an optional CREATE TABLE.
Excel (XLSX) to JSON
Convert Excel and ODS spreadsheets to JSON, with dates as ISO 8601.
Markdown to HTML
Convert Markdown into clean, sanitized HTML with GFM tables and task lists.
HTML to Markdown
Convert HTML back into Markdown, with pipe tables and your choice of bullets.
.env to JSON Converter
Convert .env files to JSON and back, following dotenv quote rules.
Number Base Converter
Convert between binary, octal, decimal, hex and any base up to 36.
CSV to Markdown Table
Convert CSV to a GitHub-flavored Markdown table with alignment and padding.
JSON to Markdown Table
Convert a JSON array of objects to a Markdown table.
Excel to HTML Table
Paste cells from Excel or Google Sheets and copy them as an HTML, Markdown or email table.
TSV to CSV Converter
Convert TSV to CSV, CSV to TSV, or change any CSV delimiter.
cURL to Code Converter
Turn a curl command into fetch, axios, Python, PHP or Go code.
HTML to JSX Converter
Convert HTML into React JSX with className, style objects and SVG fixes.
PHP Unserialize Online
Decode PHP serialize() data to JSON or print_r, and serialize JSON back.
Code Formatters & Beautifiers
JSON Formatter
Beautify, validate and minify JSON.
HTML Formatter
Beautify or minify HTML with your choice of indentation.
CSS Formatter
Beautify or minify CSS with your choice of indentation.
SCSS to CSS Compiler
Compile SCSS to plain CSS.
JSON Minifier
Strip whitespace from JSON to shrink it.
CSS Minifier
Compress CSS by removing whitespace and comments.
JavaScript Minifier
Minify JavaScript with Terser in your browser.
SQL Formatter
Format and indent SQL queries.
XML Formatter
Beautify, minify and validate XML.
YAML Formatter & Validator
Validate, tidy and re-indent YAML.
Encoders & Decoders
Base64 Encoder
Encode text or files to Base64, with full UTF-8 and emoji support.
Base64 Decoder
Decode Base64 to readable UTF-8 text.
Image to Base64
Convert an image to a Base64 data URI for HTML or CSS.
Base64 to Image
Preview a Base64 string or data URI as an image and download it.
HTML Encoder
Escape text into HTML entities: named, decimal or hex.
HTML Decoder
Turn HTML entities such as & and ’ back into plain text.
Text to Binary Converter
Convert text to UTF-8 bytes in binary, hex, decimal or octal, and back.
JSON Escape / Unescape
Escape text into a JSON string, or unescape one back to plain text.
String Escape / Unescape (Backslash)
Escape or unescape string literals for JS, Python, PHP, Bash, SQL and regex.
Hex to Text Converter
Decode hex bytes to UTF-8 text, or encode text as hex.
Generators
UUID / ULID Generator
Generate UUID v1, v3, v4, v5 and ULIDs, up to 1,000 at a time.
Cron Expression Generator
Build a cron expression by clicking, with a plain-English reading.
Password Generator
Generate random passwords and passphrases, with entropy in bits.
Lorem Ipsum Generator
Generate Lorem ipsum by paragraph, sentence, word or list item.
QR Code Generator
Create QR codes for links, text and Wi-Fi.
Meta Tag & Open Graph Generator
Generate SEO and social meta tags with a preview.
Redirect Rule Generator
Generate .htaccess and nginx redirect rules.
Cron Expression Parser
Explain a cron expression and list its next runs.
Robots.txt Generator
Build robots.txt rules and test paths against them.
XML Sitemap Generator
Turn a list of URLs into a valid sitemap.xml.
Nano ID Generator
Generate short, URL-safe Nano IDs with a collision estimate.
Random String Generator
Generate random strings from the character sets you pick.
Security & Hashing Tools
SHA Hash Generator
Generate SHA-1, SHA-256, SHA-384 and SHA-512 hashes.
HMAC Generator
Generate HMAC-SHA256 and other HMAC signatures with a secret key.
JWT Generator
Create signed JSON Web Tokens (HS256) for testing.
JWT Decoder
Decode JSON Web Tokens and verify HS256 signatures.
MD5 Hash Generator
Generate MD5 hashes from text or files.
Bcrypt Generator & Checker
Hash a password with bcrypt or verify one.
SSL Certificate Decoder (X.509 / PEM)
Decode X.509 SSL certificates and chains from PEM or DER.
API Key Generator
Generate random API keys with prefixes, checksums and SHA-256 hashes.
Basic Auth Header Generator
Build or decode HTTP Basic Authorization headers.
URL Tools
URL Encoder
Percent-encode query values or full URLs, UTF-8 safe.
URL Decoder
Decode percent-encoded text back into readable characters.
URL Parser
Split a URL into protocol, host, port, path, query and fragment.
Query String Parser
Turn a query string into decoded key-value pairs and JSON.
UTM Builder (Campaign URL Builder)
Add UTM campaign parameters to one URL or a list.
Redirect Checker (Trace Redirect Chain)
Follow every 301, 302 and meta refresh hop and see each status.
Is This Website Down? (Site Status Checker)
Check if a site is down for everyone or just you, from a neutral network.
DNS Propagation Checker
Compare A, AAAA, CNAME, MX, TXT and NS answers from 12 public resolvers.
WHOIS Lookup (Domain & IP)
Registrar, creation and expiry dates, status and nameservers for any domain or IP.
What Is My IP Address?
Your public IPv4 or IPv6 address, ISP, city and connection details.
Date & Time Tools
Date Format Converter
Convert dates between ISO 8601, RFC 2822, Unix and custom formats.
Unix Timestamp Converter
Convert Unix timestamps to dates and back.
Time Zone Converter
Convert one time across several time zones at once.
Date Difference Calculator
Years, months, days and business days between two dates.
Data Viewers
CSV to Table
Convert CSV to a table and copy it into an email or as HTML code.
JSON to Table
Turn a JSON array into a table, then copy it for email or as HTML.
PHP Array to Table
Render a PHP array as a table, then copy it for email or as HTML.
JSONPath Tester
Query JSON with JSONPath expressions.
CSV Cleaner
Trim, dedupe, filter, sort and pick columns in a CSV.
CSS & Design Tools
Color Converter
Convert colors between HEX, RGB and HSL, with a live swatch.
CSS Gradient Generator
Build linear and radial CSS gradients with a live preview.
Purge CSS
Strip CSS rules that match nothing in your HTML.
CSS Box Shadow Generator
Stack layered box shadows with a live preview and copy the CSS.
CSS Border Radius Generator
Build rounded corners and elliptical blob shapes, then copy the CSS.
CSS Flexbox Generator
See each flexbox property on real boxes and copy the CSS.
CSS Grid Generator
Build CSS grid layouts from presets and copy the CSS.
PX to REM Converter
Convert px to rem, em and pt, or a whole stylesheet.
Text & Content Tools
Regex Tester
Test a regex against sample text and see every match and group.
Diff Checker
Compare two texts by line, word or character and see what changed.
Markdown Editor & Preview
Write Markdown with a live preview and copy the sanitized HTML.
Case Converter
Convert names between camelCase, snake_case, kebab-case and more.
Slug Generator
Turn titles into clean, lowercase URL slugs with accents transliterated.
Word & Character Counter
Count words, characters, sentences and reading time as you type.
JSON Diff
Compare two JSON documents by path, ignoring key order.
Sort Lines
Sort lines A to Z, naturally, numerically or by length.
Remove Duplicate Lines
Dedupe a list, keeping the first or last copy of each line.
Find and Replace
Replace text with plain or regex rules, applied in order.