Developer Tools
183+ free tools for everyday development work — format, validate, encode, convert and generate. Everything runs in your browser, so nothing you paste is uploaded.
AI Developer Tools
About these tools →- Prompt Token CounterEstimate token counts and API costs for prompts across GPT-4, Claude, and Gemini.
- Text Chunk Splitter — LangChainLangChain TextChunkSplitter — recursive character text splitter for RAG and LLM pipelines. Split text by token count or character count, configure chunk size and overlap, choose separator presets (paragraph, sentence, Markdown, Python, JS). Export chunks as JSON, JSONL, or LangChain Document objects.
- JSON → TypeScript InterfaceGenerate TypeScript interfaces and types from any JSON object.
- JSON → Python DataclassGenerate Python dataclasses from JSON with type hints — supports nested objects, Optional fields, and List types. Works with Pydantic and FastAPI.
- JSON to OpenAI Function Schema GeneratorGenerate OpenAI function calling schema from any JSON — supports freeform input types, tool use, nested objects, required fields, and strict mode. Paste JSON and get a ready-to-use OpenAI tools schema instantly. Free, browser-based.
- JSON → Pydantic v2 ModelGenerate a Pydantic v2 BaseModel class from any JSON sample — infers types, Optional fields, datetime, EmailStr, UUID, and nested models. Ready for FastAPI.
- JSON → Zod SchemaGenerate a TypeScript Zod validation schema from JSON — smart inference: email→.email(), URL→.url(), UUID→.uuid(), integers→.int(). Includes z.infer type export.
- JSON → Prisma SchemaGenerate a Prisma model from a JSON sample — infers @id, @unique, @default, @updatedAt, nested models. Supports PostgreSQL, MySQL, and SQLite.
- JSON → Go StructConvert JSON to a Go struct with json/yaml/db/xml struct tags — PascalCase fields, acronym fixes (ID, URL, API), nested structs, omitempty and pointer options.
- Go Struct Tag GeneratorAdd json, yaml, db, xml, form, and bson struct tags to any Go struct — PascalCase fields auto-converted to snake_case tag values. Replaces or adds tags instantly.
- Regex ExplainerExplain any regular expression in plain English — colour-coded breakdown of anchors, character classes, quantifiers, groups, lookaheads, and flags. Includes 6 quick-load examples.
- AI API Cost CalculatorCompare AI API costs across 20+ models — GPT-4o, Claude 3.5, Gemini 2.0, Llama 3.3, Mistral. Enter token counts + requests to see cost per request and total cost side by side.
- JSONL Dataset ValidatorValidate JSONL files for OpenAI fine-tuning — checks message structure, roles (system/user/assistant), token counts per example, and estimates training cost. File stays in your browser.
- LLM Context Window VisualizerPaste your full prompt and see how much of the model's context window it fills — visual bar, token count, and remaining capacity for 12 models (GPT-4o, Claude, Gemini, Llama, Mistral).
- LLM Output JSON ExtractorExtract clean JSON from raw LLM output — strips explanation text, markdown code fences, and prose. Handles ```json blocks, embedded JSON objects, and pure JSON responses.
- AI Model Comparison TableCompare 22 LLM models — GPT-4o, Claude 3.5, Gemini, Llama, Mistral, Cohere. Filter by provider, context window, price, speed, open-source status. Sort by cost or capability.
- Prompt GeneratorBuild structured prompts using proven templates: chain-of-thought, few-shot, role, and more.
- AI API Request BuilderGenerate ready-to-run curl, Python, and JS code for OpenAI, Anthropic, and Gemini APIs.
- Markdown → HTML ConverterConvert Markdown to clean HTML with live preview — perfect for AI-generated content.
DevOps Tools
About these tools →- Cron GeneratorCron generator and cron expression builder — build cron expressions visually with dropdowns and labels. Preview the next 10 scheduled run times instantly. Free online cron expression generator supporting 5-field and 6-field formats.
- Cron Expression ParserParse a cron expression and see the next scheduled runs.
- .env File GeneratorBuild .env files visually with key-value pair editor.
- Gitignore GeneratorGitignore generator — generate .gitignore files for any programming language, framework, or IDE. Select Node.js, Python, React, Java, Go, Rust, and more — get a complete, ready-to-use .gitignore file instantly.
- Dockerfile GeneratorGenerate Dockerfiles for common runtimes and frameworks.
- Docker Compose GeneratorGenerate docker-compose.yml files with multiple services visually.
- Kubernetes YAML GeneratorGenerate Kubernetes Deployment and Service YAML manifests.
- Semver Range CheckerTest whether a version satisfies a semver range — supports ^, ~, >=, <, ||, and *, plus batch checking of multiple versions at once. Uses the official semver npm library.
Security & Hashing Tools
About these tools →- SHA1 Hash GeneratorGenerate SHA-1 hash of any text string.
- SHA256 Generator OnlineSHA256 online — generate a SHA-256 cryptographic hash of any text or string instantly in your browser. Free SHA256 generator and SHA-256 hash checker — no data sent to servers.
- SHA512 Hash GeneratorGenerate SHA-512 cryptographic hash of text.
- HMAC GeneratorGenerate HMAC signatures using SHA-256 or other algorithms.
- AES EncryptorEncrypt any text with AES-256-CBC using a random or custom hex key — outputs IV-embedded Base64 or Hex ciphertext.
- AES DecryptorDecrypt AES-256-CBC ciphertext back to plaintext using your secret hex key — supports Base64 and Hex ciphertext.
- Password List GeneratorPassword list generator — create a bulk list of random passwords with custom length and character sets. Also used as a password list maker, password list creator, and password generator list. All passwords generated locally in your browser, never transmitted.
- Bcrypt Hash GeneratorGenerate and verify bcrypt password hashes with configurable cost factor (rounds). All hashing runs in your browser using bcryptjs — your password is never transmitted.
- TOTP 2FA Code GeneratorGenerate live TOTP 6-digit codes from a base32 secret key — same algorithm as Google Authenticator and Authy. Uses WebCrypto HMAC-SHA1. All computation in the browser.
- Password Strength CheckerCheck password strength with entropy-based scoring, time-to-crack estimation, and detailed criteria feedback. Checks for common passwords, repeats, and sequences. Runs entirely in browser.
- JWT Generator (HS256)Create and sign JSON Web Tokens with a custom header, payload, and HMAC secret using WebCrypto. Generates real HS256 JWTs — colour-coded header, payload, and signature. Browser-only.
- File Hash CalculatorDrag-drop any file to calculate its SHA-256, SHA-512, SHA-1, and MD5 hash instantly. Verify a downloaded file against a published checksum. File never leaves your browser.
CSS & HTML Tools
About these tools →- CSS Gradient GeneratorCSS gradient generator — create linear and radial CSS gradients visually. Also called CSS generator gradient or CSS background gradient builder. Pick colors, angle, and type — get copy-ready CSS gradient code.
- CSS Box Shadow GeneratorCSS box shadow generator — build and preview CSS box-shadow values visually with live output. Also called CSS shadow generator or box shadow CSS generator. Copy the ready-to-use CSS code instantly.
- CSS Flexbox GeneratorFlex CSS generator — generate CSS flexbox layouts with a live visual preview. Also called flexbox generator or flex layout builder. Set justify-content, align-items, flex-wrap, and gap — copy the ready CSS code.
- CSS Grid GeneratorCSS grid generator — create CSS grid layouts with column, row, and gap controls. Also called grid generator or grid CSS generator. Set grid-template-columns, rows, and gaps visually — copy the output CSS instantly.
- CSS Clamp CalculatorGenerate fluid responsive CSS clamp() values for any property.
- Color Contrast CheckerCheck WCAG AA/AAA color contrast ratios for accessible text and backgrounds.
- CSS Unit ConverterConvert between px, rem, em, pt, vw, and vh CSS units instantly.
- Aspect Ratio CalculatorCalculate aspect ratios from dimensions, reverse-calculate missing dimensions, and resize proportionally with common presets for video, photo, and CSS layouts.
- HTML → JSX ConverterConvert HTML to React JSX — transforms class→className, for→htmlFor, onclick→onClick, inline styles to JS objects, and adds self-closing tags for void elements automatically.
- CSS Specificity CalculatorCalculate CSS selector specificity in (a,b,c) format — enter selectors one per line, sorted by specificity score. Handles IDs, classes, attributes, pseudo-classes, :not(), :is(), and element selectors.
SEO Tools
About these tools →- Meta Tag GeneratorGenerate HTML meta tags for title, description, and keywords.
- Open Graph GeneratorCreate Open Graph tags for rich social media previews.
- Robots.txt GeneratorBuild robots.txt files to control search engine crawlers.
- Sitemap Generator FreeXML sitemap generator online — generate a sitemap.xml for any website. Add URLs with custom priority, change frequency, and last-modified dates. Free online website sitemap generator and XML sitemap builder — no login, no upload required.
- HTTP Status Code LookupLook up HTTP status codes with descriptions and meanings.
Web Developer Tools
About these tools →- User Agent ParserParse any User-Agent string into browser, OS, and device.
- Curl to FetchConvert curl commands to JavaScript fetch() code.
- HTTP Header CheckerInspect HTTP response headers for any URL.
- REST API TesterSend GET, POST, PUT, PATCH, DELETE requests with headers, query params, and JSON body. View pretty-printed responses with status codes.
- CSP Header GeneratorBuild Content Security Policy headers interactively — toggle directives, configure source lists, and get the header value, Nginx config, Apache config, and HTML meta tag output.
- IP Subnet / CIDR CalculatorCalculate network address, broadcast, subnet mask, wildcard mask, host range, and usable host count from any CIDR notation. Identifies private ranges and IP class.
- MIME Type FinderLook up MIME types by file extension or search by content type. Covers images, video, audio, fonts, Office formats, and developer file types — 55+ MIME types with copy support.
- Fetch → cURL ConverterConvert JavaScript fetch() code to an equivalent cURL command — parses URL, method, headers, and JSON body automatically. Paste the fetch() call and get a terminal-ready cURL command.
Encoding & Decoding Tools
About these tools →- Base64 EncoderEncode plain text or binary data to a Base64 string instantly — supports full UTF-8.
- Base64 DecoderDecode a Base64 string back to plain text — handles standard and UTF-8 Base64.
- URL EncoderPercent-encode a string so it is safe to use in URLs, query strings, and API requests.
- URL DecoderDecode percent-encoded (URL-encoded) strings back to readable text — handles full UTF-8.
- JWT DecoderDecode JSON Web Tokens (JWT) headers and payloads.
- HTML Entity EncoderConvert special characters (&, <, >, ") to safe HTML entities — prevents XSS attacks.
- HTML Entity DecoderDecode HTML entities (&lt;, &amp;, ©) back to their original characters.
- Text to UnicodeConvert any text to Unicode code points in U+XXXX format — supports emoji and all scripts.
- Unicode to TextConvert Unicode code points (U+XXXX) back to readable text — supports the full Unicode range including emoji.
- Text to BinaryConvert plain text to 8-bit binary (0s and 1s) — one byte per character, space-separated.
- Binary to TextDecode binary (8-bit groups of 0s and 1s) back to readable ASCII text.
- JSON Escape / UnescapeEscape special characters in JSON strings or unescape them.
- HTML Tag RemoverStrip all HTML tags from text, leaving only plain content.
- ROT13 Encoder / DecoderApply ROT13 cipher to text — works as both encoder and decoder.
- HTML Entity ConverterConvert special characters to named HTML entities (&, <, ©) and back.
- Unicode Escape GeneratorConvert text to \uXXXX Unicode escape sequences and decode them back.
- URL Slug GeneratorConvert any title or text into a clean, SEO-friendly URL slug.
- Image → Base64 ConverterDrag and drop any image (PNG, JPG, WebP, SVG, GIF) to get the Base64 data URI and raw Base64 string. Use directly in HTML img src, CSS background-image, or JSON APIs. File stays in browser.
- Base64 → Image PreviewPaste a Base64 string or data URI to decode and preview the image instantly. Auto-detects MIME type from the binary signature. Supports PNG, JPEG, GIF, WebP, SVG, and BMP.
Code Formatter Tools
About these tools →- JSON FormatterFormat and prettify JSON data with ease.
- HTML FormatterPrettify or minify HTML markup.
- CSS Minifier OnlineCSS minify tool — minify CSS online instantly. Removes whitespace, comments, and redundant rules. Free CSS minification test and CSS compressor — paste and copy minified CSS in seconds. No upload, no login.
- JS MinifierMinify JavaScript code quickly.
- SQL FormatterFormat SQL queries with proper indentation.
- YAML FormatterParse, validate, and format YAML documents.
- JSON MinifierMinify JSON by removing all unnecessary whitespace.
- CSS BeautifierBeautify and format minified CSS code with proper indentation.
- XML FormatterFormat and prettify XML documents with proper indentation.
- JSONPath TesterTest JSONPath expressions against JSON data interactively. Supports all JSONPath operators: recursive descent (..), wildcards ([*]), filter expressions ([?(@.price < 10)]), and array slices.
- JSON Schema GeneratorAuto-generate a JSON Schema draft-07 definition from any sample JSON — detects types, required fields, and common string formats (email, date-time, UUID, URI). Browser-based.
Validators & Testers
About these tools →- JSON ValidatorValidate JSON structure and find syntax errors.
- Regex TesterTest regular expressions against target strings.
- Text Diff CheckerCompare two pieces of text to find differences.
- XML Validator OnlineXML validator online — validate XML syntax instantly in your browser. Check for unclosed tags, bad nesting, missing attributes, and malformed structure. Free XML checker and XML syntax validator — no upload, no login, works offline.
- YAML ValidatorValidate YAML syntax and report any parse errors.
- IP Address ValidatorValidate IPv4 and IPv6 addresses and detect type and scope.
- JSON Schema ValidatorValidate JSON against a JSON Schema definition. Supports draft-07 keywords: type, required, properties, additionalProperties, enum, minLength, maxLength, pattern, minimum, maximum, items.
Data Conversion Tools
About these tools →- JSON to CSVConvert JSON arrays to CSV spreadsheet format instantly.
- CSV to JSONConvert CSV data to structured JSON format.
- JSON to XMLTransform JSON objects into valid XML markup.
- XML to JSONParse XML documents and convert them to JSON.
- URL ParserParse URLs into protocol, host, path, query, and hash parts.
- Query String ParserParse URL query strings into key-value pairs.
- YAML to JSONYAML to JSON converter — convert YAML documents to JSON format instantly in your browser. Paste YAML, get valid JSON output. Free online YAML-to-JSON tool with syntax validation.
- YAML to XMLConvert YAML documents to XML format.
- XML to CSVExtract tabular data from XML and export as CSV.
- CSV to XMLConvert CSV rows into structured XML documents.
- JSON Array SorterSort JSON arrays by key, value, or custom order.
- JSON Compare ToolDiff two JSON objects and highlight additions and removals.
- JSON Key ExtractorExtract all keys from a JSON object at any depth.
- JSON Key SorterSort JSON object keys alphabetically (A→Z or Z→A), with deep sort support.
- PHP print_r() ParserConvert PHP print_r() output into JSON, JavaScript, Python, or PHP array.
- PHP var_dump() ParserParse PHP var_dump() output — with type annotations (string, int, float, bool, NULL, array, object) — and convert to JSON, JavaScript, Python, or PHP array.
- JSON Lines to ArrayConvert NDJSON / JSON Lines (one object per line) to a JSON array.
- JSON Size CalculatorCalculate JSON payload size, minified savings, key count, and nesting depth.
- JSON → YAML ConverterConvert JSON to YAML instantly — paste JSON and get clean, human-readable YAML output. Preserves all types: strings, numbers, booleans, arrays, and nested objects.
- CSV → HTML TableConvert CSV data to a styled HTML table with live preview. Choose from 7 themes (Clean, Dark, Striped, Minimal, Ocean, Sunset, Forest), configure alignment, responsive mode, hover, borders, compact padding, and rounded corners. Download as .html.
- JSON → HTML TableConvert a JSON array of objects (or 2-D arrays) to a fully styled HTML table. Auto-detects headers from keys, handles nested values, supports 7 themes, alignment, responsive scroll, and download.
- XML → HTML TableParse XML with repeating child elements and convert to a styled HTML table. Auto-detects row elements and uses tag names as column headers. Supports all 7 themes, alignment and responsive mode.
- MySQL CLI → HTML TablePaste MySQL CLI query output (the +----+------+ border format) and convert it to a polished HTML table. Supports all formatting options: themes, responsive, hover, alignment, caption, borders, compact.
- HTML Table → CSVExtract data from any HTML <table> and export as CSV. Detects <th> headers and <td> rows, handles quoted values, and outputs RFC 4180 compliant CSV. Paste any web table HTML.
- HTML Table → JSONConvert an HTML <table> to a JSON array of objects — column headers become keys, each row becomes an object. Perfect for extracting web table data for APIs or databases.
- HTML Table → XMLConvert an HTML <table> to structured XML. Each row becomes a <row> element with child tags named after column headers. Tag names are sanitised to valid XML identifiers automatically.
Generator Tools
About these tools →- UUID GeneratorGenerate secure UUIDs (v4) individually or in bulk.
- Password GeneratorCreate strong, random passwords.
- Lorem Ipsum GeneratorGenerate placeholder text for layouts.
- QR Code GeneratorCreate QR codes from text or URLs.
- MD5 Hash GeneratorCompute MD5, SHA-1, and SHA-256 hashes for strings.
- Random String GeneratorGenerate random strings with custom length and character sets.
- Unix Time GeneratorGet the current Unix timestamp or convert a date to Unix time.
- Color Palette GeneratorGenerate color palettes: shades, complementary, analogous, and triadic.
- Random Color GeneratorGenerate random HEX, RGB, and HSL colors in bulk.
- SVG ViewerPaste and preview SVG code with zoom and background controls.
- List to Code ArrayConvert a text list into a JSON, JavaScript, PHP, Python, Java, or C# array with one click.
- List to Code ObjectConvert key=value pairs into a JSON object, JavaScript object, PHP array, or Python dictionary.
Converter Tools
About these tools →- Timestamp ConverterConvert Unix timestamps to readable dates.
- Case ConverterConvert text between various letter cases.
- Color ConverterConvert between HEX, RGB, and HSL color formats.
- Number Base ConverterConvert numbers between Binary (base 2), Octal (base 8), Decimal (base 10), Hex (base 16), and Base64 instantly. Includes nibble breakdown view for binary. Supports large numbers with BigInt.
Text Utility Tools
About these tools →- Remove Duplicate LinesRemove duplicate lines online — remove repeated lines from text and keep only unique lines. Also called remove duplicates online, deduplicate text, or unique line filter. Paste text, remove duplicates instantly, copy clean output.
- Sort Text LinesSort lines alphabetically, by length, or reverse.
- Word CounterCount words, characters, sentences, and paragraphs.
- Character CounterDetailed character frequency analysis for any text.
- Text ReverserReverse characters, words, or lines in any text.
- Text CleanerRemove extra spaces, line breaks, and normalize whitespace.
- Line Numbering ToolAdd line numbers to any text block.
- Line Break RemoverRemove line breaks to join text into a single line.
- Text Shuffle GeneratorRandomly shuffle characters, words, or lines in text.
- Text Column FormatterAlign delimited text into evenly spaced columns.
- Text RepeaterRepeat any text N times with a custom separator.
- Text Line SplitterSplit text by any delimiter and display each part on its own line.
- Text Column ExtractorExtract a specific column from CSV, TSV, or any delimited text.
- Whitespace RemoverRemove extra spaces, trim lines, strip blank lines, or eliminate all whitespace.
- Substring Selector & Code GeneratorVisually select any part of a string to get its start index, end index, and length — then instantly generate substring extraction code in JavaScript, Python, Java, PHP, C#, and Go. Free, client-side, no signup.
- Reading Time EstimatorEstimate reading and speaking time for any text. Shows word count, character count, sentence count, and Flesch Reading Ease score with grade level. Adjustable reading speed (WPM).
Date & Time Tools
About these tools →- Timezone ConverterConvert times between any two world timezones.
- ISO Date ConverterConvert dates to and from ISO 8601 format.
- Date DifferenceCalculate the exact difference between two dates.
- Working Days CalculatorWorking days calculator — count working (business) days between two dates online. Exclude weekends and custom holidays. Also called business days calculator or weekday counter. Free, instant, browser-based.
- Date Format Code GeneratorGenerate date formatting code in JavaScript (dayjs, moment, native), Python, Java, PHP, MySQL, PostgreSQL, SQL Server, C#, and Go from a visual format builder. Supports date arithmetic, Unix timestamps, and preset formats. Free, instant, browser-based.
SQL Tools
About these tools →- SQL MinifierRemove whitespace and comments from SQL queries to produce compact, single-line output.
- JSON → SQL INSERT GeneratorConvert a JSON object or array into SQL INSERT statements. Strings are quoted, numbers unquoted, nulls become NULL.
- CSV → SQL INSERT GeneratorConvert CSV data into SQL INSERT statements. Numbers are auto-detected; the header row becomes the column list.
- SQL Query BuilderBuild SELECT queries visually — choose columns, add WHERE conditions, ORDER BY, and LIMIT without writing SQL by hand.
- SQL IN Clause GeneratorPaste a list of values (one per line) and get a correctly formatted SQL IN clause. Numbers are automatically unquoted.
- SQL WHERE Clause GeneratorConvert key=value pairs into a SQL WHERE clause with AND-joined conditions. Handles strings, numbers, and booleans.
- SQL Table CreatorGenerate CREATE TABLE DDL from plain field definitions. Supports MySQL, PostgreSQL, MS SQL Server, and SQLite with auto-increment PK.
- SQL UPDATE Query GeneratorGenerate UPDATE statements from key=value pairs. Set the table name and WHERE condition to target the correct rows.
- SQL DELETE Query GeneratorGenerate DELETE or TRUNCATE statements. Choose between single row (by PK), custom WHERE condition, or full table truncation.
- SQL → JSON ConverterConvert MySQL CLI table output (with +--+ borders), tab-separated, or pipe-separated SQL results to a JSON array.
- SQL Escape String ToolEscape or unescape SQL string values — single quotes are doubled per the SQL standard. Includes escape and unescape modes.
- SQL Case ConverterConvert SQL keywords to UPPERCASE or lowercase while leaving column names, table names, and string values unchanged.
- MongoDB → SQL ConverterConvert MongoDB queries (find, insert, update, delete) to SQL. Supports $gt, $lt, $in, $regex, .sort(), .limit(), and projections.
- SQL JOIN BuilderBuild SQL JOIN queries visually — choose join type (INNER, LEFT, RIGHT, FULL), ON condition, columns, WHERE, ORDER BY, and LIMIT.
- SQL UPSERT GeneratorGenerate INSERT ON DUPLICATE KEY UPDATE (MySQL), ON CONFLICT DO UPDATE (PostgreSQL), INSERT OR REPLACE (SQLite), or MERGE (MSSQL).
- SQL ALTER TABLE GeneratorGenerate ALTER TABLE DDL for MySQL, PostgreSQL, MSSQL, and SQLite. Add, modify, drop, rename columns; manage indexes and constraints.
- SQL Pagination GeneratorGenerate paginated SQL for any database — LIMIT/OFFSET (MySQL/PostgreSQL), OFFSET FETCH NEXT (MSSQL), ROWNUM (Oracle). Includes count query.
- SQL Type MapperCross-database type reference table — compare MySQL, PostgreSQL, MS SQL Server, SQLite, and Oracle type equivalents for 20 common types.
- SQL Stored Procedure TemplateGenerate stored procedure and function scaffolding for MySQL, PostgreSQL, and MS SQL Server. Includes correct DELIMITER / $$ / BEGIN syntax.
- SQL GRANT / REVOKE GeneratorGenerate GRANT and REVOKE permission statements for specific tables, databases, or all schemas. Select individual privileges or ALL PRIVILEGES.
- SQL → PHP Array ConverterConvert MySQL CLI output (+--+ borders), tab-separated, or pipe-separated SQL results into a PHP associative array ready to paste into code.