Developer Tools
The daily developer toolbelt — formatters, encoders, decoders, hashers and testers — with nothing sent to a server.
68 tools, all running in your browser.
Fig 1 Bytes you can see
Move across to read a byte · ← →
Each row of holes is one byte of {"ok":true}. Formatters, encoders and hash tools here all read your bytes like this reader does, in your own browser.
Most used
Base64 Encoder / Decoder Encode or decode Base64 text and files, build data URIs, and switch to the URL-safe alphabet. Full UTF-8 support, everything stays on your device. Image to Base64 Turn any PNG, JPG, GIF, WebP or SVG into raw Base64, a data URI and ready-made HTML, CSS and Markdown snippets. Nothing is uploaded. JSON Formatter Beautify, minify and validate JSON with the exact line and column of any error, sort keys, escape strings and generate TypeScript interfaces. JSON Validator Find the exact line, column and cause of a JSON error, then fix trailing commas, single quotes and comments in one click. Nothing is uploaded. JWT Decoder Decode a JSON Web Token header, payload and signature, read the claims in plain English, and verify HS256/384/512 — the token never leaves your browser. PX to REM Converter Convert px to rem at any root font size, rewrite every px in a pasted stylesheet at once, and keep a permanent 1–96 px reference table to hand. SQL Formatter Beautify SQL for Postgres, MySQL, T-SQL, Oracle, SQLite, Snowflake and BigQuery. Runs in your browser, so production queries stay on your machine. Subnet Calculator IPv4 and IPv6 subnetting: mask, wildcard, network, broadcast, host range and count, a binary view, VLSM splits and AWS/Azure/GCP reserved hosts.
Everything else
ASCII Table The full ASCII and Latin-1 table with decimal, hexadecimal, octal and binary values, control-character names and the escapes that go with them. ASCII to Hex Turn ASCII characters into their hex byte values with configurable spacing, case and prefix — and a warning for anything outside ASCII. Base32 Encoder / Decoder Encode and decode RFC 4648 Base32 and base32hex locally — the alphabet used by TOTP secrets, DNSSEC records and Tor addresses. Base64 to File Paste Base64 or a data URI and download the original file. The type is detected from the file signature, not from the string. Base64 to Image Paste a Base64 string or data URI and get an instant preview plus a downloadable PNG, JPG, GIF, WebP or SVG. Type detected from the bytes. Chmod Calculator Tick a permission grid to get the octal and symbolic mode, the setuid, setgid and sticky bits, and copy-ready chmod commands. CIDR to IP Range Expand any CIDR block into its first and last address, host range, mask and total count — for firewall rules, allowlists and audits. Code Diff Checker Compare two versions of code line by line with numbered unified or side-by-side views, whitespace options, change stats and copyable unified patch output. Color Converter Convert colors between HEX, RGB, HSL, HSV, OKLCH and CMYK, check WCAG contrast with AA and AAA badges, and build tint and shade scales instantly. Cron Expression Parser Translate a 5- or 6-field cron expression into plain English, validate every field, preview the next ten run times, and build a schedule from presets. Crontab Generator Build a cron expression from dropdowns, read it back in plain English, and see the next ten run times in any timezone. Decimal to Text Turn a list of decimal character codes into text and back, with UTF-8 or ASCII byte handling and any separator you like. EM to PX Converter Convert em values to pixels against a parent font size you set, so you can see what a nested component actually measures on screen. File to Base64 Encode a PDF, ZIP, font, certificate or audio file to Base64 or a data URI locally — no upload, no size cap, no queue. Hash Generator Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 checksums for text or any file, compare against an expected hash, and verify downloads locally. Hex to ASCII Decode hex byte values into ASCII characters, one byte per character, with clear errors for values outside the printable range. HEX to CMYK Converter Convert a screen hex colour into approximate CMYK ink percentages for print, with a clear statement of what that approximation can and cannot promise. HEX to HSL Converter Convert hex colours to HSL so you can reason in hue, saturation and lightness — the notation that makes building a colour scale straightforward. HEX to RGB Converter Convert a hex colour to RGB with a live swatch, alpha support, contrast ratios and every other CSS notation ready to copy. Hex to Text Decode hexadecimal into readable text with full UTF-8 support, any separator, 0x prefixes and a file input for hex dumps. HSL to HEX Converter Convert hsl() or hsla() values into a hex colour code, with a live swatch and every other CSS notation listed alongside it. HTML Entity Encoder Encode text to named or numeric HTML entities and decode them back, with a minimal mode that escapes only the five characters HTML actually requires. HTML Entity Reference A searchable table of HTML entities with their named, decimal and hexadecimal references — arrows, currency, maths, Greek, accents and dashes. HTTP Status Codes Every HTTP status code with what it means, what actually causes it and how to fix it — searchable, with a page per code and the RFC reference. IP Range to CIDR Convert a start and end address into the smallest exact set of CIDR blocks — the conversion security groups and route tables demand. IPv4 to Binary See an IPv4 address in binary, hex, octal and as a 32-bit integer, octet by octet, with the place-value arithmetic written out. JSON Escape Turn any text — including a whole JSON document — into a single escaped JSON string literal you can safely embed in another payload. JSON Lint A stricter read than a plain parse: syntax errors with line and column, plus warnings for duplicate keys and unsafe integers. Runs offline. JSON Minifier Strip every optional byte from a JSON document and see exactly how much you saved. The input is parsed first, so a result also proves validity. JSON to C# Classes Convert JSON into C# classes with System.Text.Json attributes, PascalCase properties, nullable reference types and List<T> collections. JSON to Go Struct Convert a JSON sample into Go structs with correct json tags, Go initialisms (ID, URL, API), int64/float64 inference and omitempty on optional keys. JSON to JSON Schema Infer a draft 2020-12 JSON Schema from example data, with types, required arrays, nested object schemas and array item types. JSON to One Line Collapse a formatted JSON document onto a single line, with or without spaces after colons and commas, for logs, env vars and shell arguments. JSON to Python Dataclass Convert JSON into Python dataclasses with modern type hints, snake_case attribute names and optional fields defaulting to None. JSON to TypeScript Turn a real API response into named TypeScript interfaces, with optional keys, union types and nested interfaces inferred from the actual data. JSON to XML Converter Build XML from JSON: prefixed keys become attributes, arrays repeat their element, and illegal key names are renamed with the changes listed. JSON to Zod Schema Turn a JSON sample into a Zod schema with nested z.object() definitions, .optional() and .nullable() modifiers and an inferred TypeScript type. JSON Unescape Turn an escaped JSON string back into readable text: \" becomes ", \n becomes a real line break, and \uXXXX becomes the character it names. MIME Types List A searchable list of MIME content types and their file extensions, with notes on the ones servers routinely get wrong. Number Base Converter Convert numbers between binary, octal, decimal, hex, base36 and any base from 2 to 36, with bitwise operations, byte grouping and a two’s-complement view. Octal to Text Decode base-8 byte values into readable text, in either direction, with padded or unpadded groups and UTF-8 or ASCII output. PX to EM Converter Convert px to em against the parent font size, with a bulk stylesheet rewrite and a note on the compounding trap that makes em surprising. PX to Percent Converter Convert a pixel font size to a percentage of its parent, the notation used for accessible base sizing and for fluid layout widths. PX to PT Converter Convert CSS pixels to typographic points and back using the fixed 96 px per inch that CSS defines, for print stylesheets and PDF work. Regex Tester Test JavaScript regular expressions live with highlighted matches, capture and named group tables, a replace preview, flags, and a built-in cheatsheet. REM to PX Converter Convert rem values back to pixels at any root font size, so you can check what a design token will actually measure on screen. RGB to HEX Converter Convert rgb() or rgba() values to a hex colour code, with alpha folded into an 8-digit hex and every other notation ready to copy. RGBA to HEX Converter Convert rgba() to an 8-digit hex code with the alpha channel preserved, plus the flat hex you would get by compositing onto a background. SQL Minifier Collapse a SQL query onto one line for a config file, an env var or a log entry. Comments optional, tokens untouched, nothing uploaded. SVG to Base64 Convert an SVG to Base64 or the smaller URL-encoded form, with copy-ready background-image, img and Markdown snippets for inline icons. Text to Hex Encode text as hexadecimal with a choice of separator, uppercase digits and 0x prefixes, plus a byte dump for any file you drop in. URL Encoder / Decoder Percent-encode or decode URLs with encodeURIComponent or encodeURI, and parse a query string into an editable table of parameters you can rebuild. UUID Generator Generate cryptographically random UUID v4 or time-ordered UUID v7 in bulk, choose the output format, and validate or detect the version of any UUID. XML Escape Convert &, <, > and quotes into XML entity references so a fragment can be embedded safely in element text or an attribute value. XML Formatter Pretty-print XML, SOAP, WSDL and config files with real indentation and attribute wrapping. Parsed by your own browser — nothing is uploaded. XML Minifier Remove insignificant whitespace and optional comments from XML, with a before-and-after size readout. Parsed first, so the output is always valid. XML to JSON Converter Convert XML to JSON with a configurable attribute prefix, text key and forced-array rules — and an honest note wherever the mapping is lossy. XML Unescape Turn entity references back into characters, including numeric forms such as   and  , so escaped markup becomes readable again. XML Validator Check whether XML is well-formed and get the line, column and a plain-English explanation of the first error instead of a cryptic parser dump. XML Viewer Explore a large XML document as a collapsible tree — element names, attributes and text — with every branch expandable from the keyboard.