Developer Tools
72 free developer tools. Browser-based. No signup. Privacy-first.
What are Developer Tools?
Zerethon's developer suite includes 72 browser-based utilities designed for everyday developer workflows. Every tool runs entirely client-side — your input never reaches our servers.
Why client-side?
- Privacy: sensitive data (API keys, payloads, passwords) never leaves your device.
- Speed: no network round-trip — results appear as you type.
- Reliability: works offline once loaded.
- Cost: always free, no signup or rate limits.
Browse Developer Tools
Formatters & Minifiers · 18
JSON Formatter
Format, validate, and minify JSON online. Free, no signup — your data never leaves your browser.
Open toolSQL Formatter
Format SQL queries online — beautify MySQL, PostgreSQL, SQLite, SQL Server, Oracle, and BigQuery.
Open toolHTML Formatter & Minifier
Beautify or minify HTML in your browser. Pure client-side — your markup never leaves your device.
Open toolCSS Formatter & Minifier
Beautify or minify CSS rules instantly in your browser. Free, no signup, no upload.
Open toolYAML Formatter & Validator
Validate, reformat, and minify YAML in your browser. Catches syntax errors with line numbers.
Open toolXML Formatter
Beautify or minify XML using your browser's native parser. No dependencies, fast and accurate.
Open toolMarkdown Formatter
Reformat Markdown with Prettier. Consistent spacing, list markers, and link layout.
Open toolJavaScript Formatter & Minifier
Beautify with Prettier or minify in your browser. Supports modern syntax — async/await, optional chaining, JSX.
Open toolPython Formatter
Clean up Python indentation, collapse blank lines, normalize string quotes. Indentation cleaner, not full PEP-8.
Open toolPHP Formatter
Reformat PHP source in your browser. PSR-12-friendly defaults, brace-style toggle, opener normalization.
Open toolJava Formatter
Reindent Java source with K&R or Allman brace style. Pure client-side, no compile.
Open toolC# Formatter
Reformat C# source with Allman braces, auto-property normalization, and expression-bodied member tidy-up.
Open toolC / C++ Formatter
Reformat C or C++ source — brace style, indent width, and preprocessor placement controls.
Open toolRuby / Lua / Perl Formatter
Reindent Ruby, Lua, or Perl source. One tool, three keyword-driven languages.
Open toolGraphQL Formatter
Pretty-print GraphQL queries, mutations, and SDL using the official graphql/language parser.
Open toolCSS Preprocessor Converter
Convert between LESS, SCSS, SASS, Stylus, and CSS. Real compilers for "to CSS" paths, heuristics for the rest.
Open toolJavaScript Minifier
Minify JavaScript with terser. Mangle, compress, comment policies — and a before / after size comparison.
Open toolHTML Minifier
Minify HTML with html-minifier-terser. Collapses whitespace, removes comments, inline CSS / JS minification. Size savings shown live.
Open toolData Converters · 14
CSV to JSON Converter
Convert CSV (or TSV / pipe-separated) data to JSON. Auto-detects delimiter, RFC 4180 compliant.
Open toolJSON to CSV Converter
Convert a JSON array of objects to CSV. Optional dot-path flatten for nested data.
Open toolJSON to YAML Converter
Convert JSON to YAML in your browser. YAML 1.2 spec.
Open toolYAML to JSON Converter
Convert YAML to JSON in your browser. Catches syntax errors with parser messages.
Open toolJSON to XML Converter
Convert JSON to XML in your browser. Configurable root element, attribute prefix, and text key.
Open toolDelimited Text Extractor
Extract one column from CSV, TSV, or any delimited text. Pick by column number or header name. RFC 4180 compliant.
Open toolXML to JSON Converter
Convert XML to JSON in your browser. Native DOMParser with configurable attribute prefix, text key, and compact mode.
Open toolCSV to XML Converter
Convert CSV (or TSV / pipe-separated) data to XML. Configurable root and record element names. Header row becomes column tags.
Open toolCSV to SQL Converter
Generate INSERT statements from CSV. MySQL, PostgreSQL, SQLite, or SQL Server dialect, with optional CREATE TABLE.
Open toolHTML Stripper
Strip HTML tags and decode entities to plain text. Toggles for line breaks, links, and whitespace preservation.
Open toolHTML Table Extractor
Extract <table> elements from HTML into CSV, TSV, JSON, or Markdown. Picks individual tables when the page has more than one.
Open toolHTML to Markdown Converter
Convert HTML to Markdown using Turndown. ATX or Setext headings, bullet style, code-fence style — fully customizable.
Open toolMarkdown to HTML Converter
Render Markdown to HTML with live preview. GFM tables, task lists, fenced code blocks. Powered by marked.
Open toolJSON to Java POJO
Generate a Java POJO from JSON. Toggles for Jackson annotations, Lombok, or Java 16+ records. Nested objects become nested classes.
Open toolEncoding & Encryption · 7
Base64 Encoder & Decoder
Encode and decode Base64 text or files. Supports standard and URL-safe variants. Free, no signup.
Open toolURL Encoder & Decoder
Encode and decode URLs and query string parameters. Percent-encoding for safe transmission.
Open toolAES Encrypt & Decrypt
Encrypt and decrypt text with AES-256-GCM and a password. PBKDF2-SHA256 key derivation, runs entirely in your browser.
Open toolBase-N Encoder & Decoder
Encode and decode Base16, Base32 (RFC 4648), Base32 Crockford, Base85 (ASCII85), and Base91 in your browser.
Open toolUTF-8 Converter
Convert text to UTF-8 hex bytes, decimal bytes, \xAB or \u{HEX} escape sequences — and back.
Open toolHTML Entities Converter
Encode and decode HTML entities — named, decimal, and hex. 250+ HTML5 entities included.
Open toolEscape & Unescape
Escape and unescape strings for HTML, XML, Java, C#, JavaScript, JSON, CSV (RFC 4180), and SQL.
Open toolHash & Crypto · 6
MD5 Hash Generator
Compute MD5 digest of text or files (up to 50 MB) in your browser. Output in hex or Base64.
Open toolSHA-256 Hash Generator
Compute SHA-256 digest of text or files in your browser using Web Crypto API. Output in hex or Base64.
Open toolSHA-1 Hash Generator
Compute SHA-1 digest of text or files in your browser using Web Crypto API. Useful for Git commit hashes and legacy systems.
Open toolROT13 Encoder
Classic ROT13 cipher in your browser. Encoding and decoding are the same operation.
Open toolCaesar Cipher
Encrypt and decrypt with the classic Caesar shift cipher. Includes auto-detect using English letter frequency.
Open toolHash Generator — All Algorithms
Compute MD4, MD5, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA3, Keccak-256, CRC-32 and NTLM hashes of text or files in your browser.
Open toolNumbers & Bitwise · 6
Number Base Converter
Convert numbers between decimal, binary, octal and hexadecimal in a live 4-row grid. BigInt-safe with optional signed 32 / 64-bit mode.
Open toolBitwise Calculator
AND, OR, XOR, NAND, NOR, XNOR, NOT and shift operations on two BigInt operands. Results shown in decimal, binary, octal and hex at once.
Open toolIP Notation Converter
Convert IPv4 and IPv6 between dotted, decimal integer, hex, octal, binary, and canonical / expanded forms. Auto-detects the input format.
Open toolString to Hex Converter
Convert text to UTF-8 hex bytes and back. Pick from five separators on encode; decode auto-strips any common separator.
Open toolString to Binary Converter
Convert text to 8-bit binary and back. UTF-8 aware with optional byte and nibble spacing for readability.
Open toolASCII Converter
Convert characters to ASCII / Unicode codepoints in decimal, hex, binary and octal — or render a live table for any input string.
Open toolDate & Time · 3
Timezone Converter
Convert any date and time between IANA timezones. DST-aware, shareable, runs entirely in your browser.
Open toolUnix Timestamp Converter
Convert Unix timestamps (seconds or milliseconds) to ISO, UTC, RFC 2822, local, and relative formats. Live "Now" panel.
Open toolCrontab Translator
Translate a cron expression to plain English and preview the next 5 fire times. Supports standard 5-field and 6-field with seconds.
Open toolValidators & Testers · 4
JSONPath Tester
Test JSONPath expressions against your JSON. Live evaluator with path and value results, filters, slices, recursive descent.
Open toolXPath Tester
Test XPath expressions against XML or HTML using your browser's native XPath engine. Live results table.
Open toolRegex Data Generator
Generate 1–100 strings that match any regex pattern. Great for test data, fixtures, and fuzzing.
Open toolJSON5 Validator
Validate JSON5 with line and column error reporting. Supports comments, trailing commas, single quotes, hex numbers.
Open toolDiff & Compare · 2
Web & SEO · 5
Slugify URL Generator
Turn any text into a clean URL slug. Transliterates diacritics, strips punctuation, optional stopword removal.
Open toolMarkdown Table Generator
Build GitHub Flavored Markdown tables in a live grid. Paste TSV or CSV, set alignment per column.
Open toolUTM Builder
Build campaign-tagged URLs for Google Analytics, GA4, Plausible, PostHog. Validates URL and saves your last 5 locally.
Open toolURL Parser
Break a URL into scheme, credentials, host, port, path, query and hash. Percent-decoded query parameters in a live table.
Open toolHTML Playground
Live HTML / CSS / JS playground with sandboxed iframe preview. Auto-saves to localStorage. Pure client-side.
Open toolGenerators · 4
UUID Generator
Generate UUIDs online — v1, v4, v7, and Nil. Bulk generation up to 10,000. Free, no signup.
Open toolPassword Generator
Generate strong, cryptographically random passwords. Configurable length and character sets — runs in your browser.
Open toolRandom JSON Generator
Generate fake JSON from a schema using faker.js. Multi-output: JSON, CSV, TSV, XML. Free, runs in your browser.
Open toolJavaScript Obfuscator
Obfuscate JavaScript with control-flow flattening, string array, dead-code injection and identifier mangling. Three presets, runs in your browser.
Open toolText Style & Cases · 1
Text Cleanup · 1
Frequently asked questions
Are these Developer tools free?
Yes. All 72 tools are free with no signup, no rate limits, and no ads outside footer placements.
Do these tools work offline?
Yes. Once a tool page loads, the tool itself runs in your browser without needing a network connection.
Do you log my inputs?
No. Tools run entirely client-side. Your input never leaves your browser unless a tool explicitly says it makes an API call (e.g. Open Graph Preview, which fetches a URL through our server proxy).
Can I use these tools commercially?
Yes. Outputs you generate are yours. The tools themselves are operated by Zerethon — please respect rate limits on server-backed tools.
Where can I request a new Developer tool?
Tweet us or open a GitHub issue. The most-requested tools enter our roadmap quarterly.
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