185 free online tools. No signup required.
Format, validate, and beautify JSON data with error detection
Test regular expressions with real-time matching, flags support, and capture group display
Visual cron expression builder with human-readable descriptions and next run times
Decode JSON Web Tokens to inspect header, payload, and expiration status
Encode and decode text and files to and from Base64 format
Encode and decode URLs with component breakdown and query parameter parsing
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes using Web Crypto API
Generate random v4 UUIDs with bulk generation and one-click copy
Convert between Unix timestamps and human-readable dates with relative time
Format and beautify SQL queries with syntax highlighting and indentation
Minify HTML, CSS, and JavaScript code with before/after size comparison
Compare two texts side by side and highlight additions, deletions, and changes
Live Markdown editor with instant preview supporting tables, code blocks, and lists
Convert between YAML and JSON formats bidirectionally with validation
Interactive chmod permission calculator with symbolic and numeric modes
Paste a regex pattern and get a human-readable English explanation of what it does, step by step.
Design REST API endpoints with methods, paths, params, request/response bodies. Generate OpenAPI/Swagger YAML spec.
Describe what you want to do in plain English and get the right git command. Interactive decision tree approach.
Build webhook payloads for common services (Stripe, GitHub, Slack, Discord, Twilio). Generate test JSON.
Create and edit .env files with variable grouping, comments, validation. Import/export. Template generation.
Create markdown tables visually with rows/columns, alignment options, and copy markdown output
Visual builder for docker-compose.yml files with services, volumes, networks, and environment variables
Generate nginx server blocks for reverse proxy, static files, SSL, redirects, and load balancing
Generate a stylish GitHub profile README with intro, skills, stats, social links, and live preview
Analyze JavaScript/Python code for cyclomatic complexity, nesting depth, function count, and provide a score
Visual builder for DNS zone files with A, AAAA, CNAME, MX, TXT, SRV, NS records and BIND zone file export
Visualize multiple cron schedules on a 24h timeline, detect overlaps, and show next N runs
Paste JSON data to auto-generate a JSON Schema with types, required fields, and nested structures
Calculate API rate limits, token bucket parameters, burst capacity, and optimal retry timing with visual timeline
Enter CSS selectors, calculate and visualize specificity (inline, ID, class, element). Compare multiple selectors.
Press any key, show keyCode, key, code, which, location, modifier keys. Useful reference for keyboard event handling.
Build HTTP requests visually with method, URL, headers, body, auth. Generate cURL, fetch, axios, XMLHttpRequest code.
Enter Tailwind CSS classes, output the equivalent vanilla CSS properties with computed values.
Detect and display browser capabilities: WebGL, WebRTC, Service Workers, Web Audio, IndexedDB, Canvas, etc. with green/red indicators.
Calculate subnet details from CIDR notation: network address, broadcast, host range, usable hosts, wildcard mask
Analyze any IP address: class, type (public/private/loopback), binary, hex, and integer representation
Generate K8s manifests: Deployment, Service, Ingress, ConfigMap, Secret with a visual form builder
Build Terraform variable definitions with type, default, description, and validation rules
Searchable reference of essential Linux commands organized by category with examples
Interactive regex cheatsheet with categories: anchors, quantifiers, groups, character classes, lookaheads
Build SSH config file entries with Host, HostName, User, Port, IdentityFile, ProxyJump
Generate systemd unit files with [Unit], [Service], [Install] sections and common presets
Reference guide for log levels across frameworks: Log4j, Winston, Python logging, Serilog
Build common HTTP headers: Cache-Control, Content-Type, Authorization, CORS. Explain each directive
Visual Makefile builder with targets, dependencies, commands, variables and common templates
Visual package.json editor with name, version, scripts, dependencies, engines and validation
Build GitHub Actions workflows visually with triggers, jobs, and steps. Generate YAML output
Build PromQL queries visually: select metric, add labels, choose functions like rate, sum, avg
Searchable database of HTTP status codes, Unix signals, errno values, Windows HRESULT, and exit codes
Input JSON data, write JSONPath expressions, see matching results. Support dot notation, brackets, wildcards, filters.
Visual GraphQL query builder. Define types, fields, arguments. Generate query strings. Syntax highlighting.
Calculate P50, P95, P99 response times from a list of response time values. Show distribution histogram with Canvas.
Paste CSV/TSV data, view as sortable/filterable table. Column stats (min, max, avg for numbers). Export filtered data.
Paste encoded text, detect encoding type (Base64, URL-encoded, HTML entities, Unicode escapes, JWT, hex). Auto-decode.
Generate mock JSON responses for testing. Define schema (name, email, id, date, etc.), get formatted JSON output.
Visual SQL SELECT query builder. Add tables, columns, WHERE clauses, JOINs, ORDER BY, GROUP BY. Generate SQL.
Input text and regex with capture groups, extract and display all matched groups in a structured table.
Compare multiple timestamps across formats (Unix, ISO 8601, RFC 2822). Sort chronologically, show differences.
Compare two .env files side by side. Highlight added, removed, changed variables. Generate diff output.
Encode/decode HTML entities (named, numeric, hex). Quick buttons for common entities. Bulk conversion.
Parse URLs into components (protocol, host, path, query params, fragment). Build URLs from components. Copy result.
Edit TOML configuration files with syntax validation. Convert between TOML and JSON. Inline documentation.
Interactive guide to choosing a software license (MIT, Apache, GPL, BSD, etc.). Compare permissions/conditions/limitations. Generate LICENSE file.
Generate release notes from feature/fix/improvement bullet points. Multiple formats: Keep a Changelog, semantic, GitHub release style.
Estimate token count for text using BPE-like approximation. Show counts for GPT-4, Claude, Llama. Character, word, and sentence stats.
Interactive comparison table of major AI models: GPT-4, Claude, Gemini, Llama, Mistral. Context window, pricing, capabilities, release dates.
Searchable reference of prompt engineering techniques: chain-of-thought, few-shot, system prompts, personas, output formatting.
Convert data between fine-tuning formats: JSONL (OpenAI), CSV, Alpaca format. Add system/user/assistant messages.
Reference for embedding models: dimensions, size, performance benchmarks. OpenAI ada-002, Cohere, sentence-transformers.
Generate AI model cards with intended use, limitations, training data info, performance metrics, ethical considerations.
Format ML benchmark results into clean comparison tables. Input model names and scores, generate markdown/HTML table.
Interactive guide to data labeling/annotation best practices. Labeling guidelines template generator. Quality metrics reference.
Paste ABI event signature, decode event topic hashes. Reference of common ERC-20/721 events and function selectors.
Display current screen/viewport info: resolution, DPR, viewport size, orientation, color depth, touch support, OS/browser detection.
Upload a JPEG image and read its EXIF metadata: camera model, date, GPS coordinates, exposure, ISO, focal length, and more. Fully client-side.
Searchable reference of all ARIA roles with descriptions, required attributes, usage examples. Grouped by category (landmark, widget, structure).
Searchable database of ISO 639 language codes, ISO 3166 country codes, BCP 47 locale tags. Copy formatted codes.
Test right-to-left text rendering. Input text, toggle LTR/RTL/auto direction. Preview with different CSS direction settings.
Analyze text for Unicode properties: scripts used, character categories, bidi levels, code points. Detect mixed scripts.
Compare two JSON translation files for missing keys, extra keys, empty values. Diff view with highlighted issues.
Format dates as relative time ("2 hours ago", "in 3 days") in multiple locales using Intl.RelativeTimeFormat. Preview all locales.
Preview how numbers display across locales using Intl.NumberFormat: currency, decimal, percent, unit formatting.
Preview date/time formatting across locales using Intl.DateTimeFormat. All options for dateStyle, timeStyle, custom patterns.
Show Intl.PluralRules categories (zero, one, two, few, many, other) for different locales. Interactive tester with custom numbers.
Paste text, detect dominant script direction (LTR/RTL), identify scripts present, suggest HTML dir attribute value.
Sort strings using locale-aware comparison (Intl.Collator). Compare results across locales. Handle diacritics and special chars.
Generate test case templates: given/when/then format, boundary values, equivalence classes. Input feature description, output structured test cases.
Interactive code review checklist: logic, security, performance, readability, tests, documentation. Track completed items.
Plan load tests: calculate concurrent users, requests per second, ramp-up time. Generate test scenarios. k6/JMeter config hints.
Generate boundary value test cases from input constraints. Min, min+1, nominal, max-1, max. Handle multiple parameters.
Create decision tables with conditions and actions. Generate all condition combinations. Identify missing rules.
Input test cases with risk, frequency, impact scores. Calculate priority. Generate ordered test execution plan.
Build API test scenarios: endpoint, method, headers, body, expected status, response validation rules. Export as JSON.
Set performance budgets: total page weight, JS size, CSS size, image budget, font budget. Track against targets.
Generate test data: valid/invalid emails, phone numbers, dates, names, addresses. Edge cases included. Bulk CSV export.
Interactive ASCII/Unicode table: decimal, hex, octal, character, description. Filter printable, control, extended. Click to copy.
Create entity-relationship diagrams: add entities with fields/types, show as list-based visualization. Export as JSON.
Visual table schema builder: columns with name, type, constraints. Generate SQL CREATE TABLE for MySQL/PostgreSQL/SQLite.
Design MongoDB schemas. Nested objects, arrays, types. Generate JSON schema and sample documents.
Searchable Redis command reference by data type (String, List, Set, Hash, etc.). Syntax and examples.
Input table schema and queries, suggest indexes. Best practices guide.
Build connection strings for PostgreSQL, MySQL, MongoDB, Redis, SQLite. Input fields, copy URI.
Generate migration scripts: add/rename column, create table, add index. Output for raw SQL.
Generate SQL INSERT statements with realistic fake data. Define columns and types.
Generate API docs from endpoint definitions. Path, method, params, examples. Markdown output.
Define GraphQL types, fields, relationships, enums. Generate SDL.
Paste access logs, parse: top IPs, status codes, top URLs, request methods. Chart.
Build CORS configs visually. Generate Express/nginx config code.
Configure rate limiting parameters. Generate Express middleware code.
Design webhook event schemas and payloads. Generate documentation.
Design message queue topics with schemas. Generate config documentation.
Real-time frequency spectrum visualization from microphone input using Web Audio API
Connect to WebSocket URLs, send/receive messages, view message log with timestamps. Connection status indicator.
Connect to SSE endpoints, display events in real-time log. Auto-reconnect option.
Reference guide for gRPC concepts: unary, server-streaming, client-streaming, bidirectional. Proto file syntax reference.
Interactive visualization of OAuth 2.0 flows: Authorization Code, Implicit, Client Credentials, Device Code. Step-by-step diagrams.
Compare API versioning strategies: URL path, query param, header, content negotiation. Pros/cons matrix.
Paste OpenAPI/Swagger YAML or JSON, validate structure, check for common issues. Display endpoints summary.
Interactive comparison of HTTP versions: features, performance, multiplexing, header compression, QUIC. Visual diagrams.
Interactive guide for REST API naming: resources, collections, actions, query params. Validate endpoint names.
Calculate exponential backoff schedules for webhook retries. Visualize retry timing. Configure base delay, max retries, jitter.
Design API pagination: offset/limit, cursor-based, keyset. Generate response format with metadata. Best practices.
Test Accept header content negotiation logic. Input available types and Accept header, show which type wins.
Searchable database of MIME types: application/, text/, image/, audio/, video/, font/. With file extensions.
Build Cache-Control headers visually: max-age, no-cache, no-store, public/private, must-revalidate. Generate header string.
Design consistent API error responses: status codes, error codes, messages, details. Generate error handling code.
Interactive guide: synchronous (REST, gRPC) vs asynchronous (event-driven, message queue). Decision framework.
Paste full CSS and HTML to identify critical above-the-fold CSS rules and generate inline critical CSS snippets
Generate lazy loading code for images with native loading="lazy", Intersection Observer, and placeholder strategies
Generate preconnect, prefetch, preload, and prerender link tags for web performance optimization
Estimate Core Web Vitals scores from manual inputs: LCP, FID, CLS. Grade each as Good, Needs Improvement, or Poor
Compare font loading strategies and generate optimal @font-face declarations with font-display, preload, and fallback options
Generate responsive image srcset and sizes attributes with breakpoints, widths, and picture element markup
Estimate bundle sizes for common npm packages, compare alternatives, and visualize tree-shaking savings
Preview what content appears above the fold at different viewport sizes with a visual fold line indicator
Generate service worker code with cache-first, network-first, and stale-while-revalidate strategies plus offline fallback
Test viewport meta tag configurations, preview behavior at different screen sizes, and get recommended settings
Define character subsets for web fonts including Latin, Latin Extended, and custom characters. Generate unicode-range CSS
Paste script tags to categorize third-party scripts by type and estimate their loading impact on page performance
Set page weight budgets per resource type and track against targets with visual gauges and alerts
Guide for script loading with async vs defer vs module, including a decision tree, impact analysis, and code generation
Estimate Lighthouse performance score from manual metrics including FCP, LCP, TTI, TBT, CLS, and Speed Index with calculation breakdown
Enter filenames one per line, apply rename rules like prefix, suffix, and find/replace, then see preview
Paste JSON data and apply transforms like sorting keys, filtering fields, and flattening nested objects
Enter cron expressions and view the next 5 run times for each one with human-readable descriptions
Add states and transitions to build a state machine, displayed as a text-based diagram with export
Track feature flags with name, on/off status, and environment in a table view with localStorage persistence
Build notification messages with title, body, and type (info/warning/error/success) with styled preview
Reference guide of error handling patterns including retry, circuit breaker, and fallback with expandable sections
Define pipeline stages with health status (green/yellow/red) and view them as a visual status board
Build runbooks by adding titled sections with step lists and export the complete runbook as text
Generate deep link URLs: app links (Android), universal links (iOS), custom URL schemes. Generate associated domains config.
Reference chart of all popular mobile device viewports: iPhone, Samsung, Pixel, iPad. Width, height, DPR, CSS pixels.
Reference guide for mobile app permissions: iOS and Android. What each permission grants, user-friendly explanations.
Interactive reference of mobile gestures: tap, swipe, pinch, rotate, long press, 3D touch. Usage patterns, code hints.
Manage semantic versioning: major.minor.patch. Increment buttons, build number, version code calculator.
Generate project README files: title, description, installation, usage, contributing, license. Multiple styles. Copy markdown.
Write API changelogs: version, date, added/changed/deprecated/removed/fixed/security sections. Keep a Changelog format.
Generate code documentation templates: function docs, class docs, module docs. JSDoc/Python docstring/JavaDoc format.
Generate ADR (Architecture Decision Records): title, status, context, decision, consequences. Numbered and dated.
Create operational runbooks: service name, alerts, troubleshooting steps, escalation, rollback procedures.
Generate tech specs: overview, goals, non-goals, design, API changes, testing plan, rollout plan.
Guide for writing good error messages: what happened, why, how to fix. Before/after examples. Interactive analyzer.
Interactive guide to commit message conventions: Conventional Commits, Angular, custom. Generator and validator.
Build PR templates: description, type of change, checklist, testing, screenshots. Multiple presets. Copy markdown.
Build GitHub issue templates: bug report, feature request, question. Required fields, labels. Copy YAML/markdown.
Generate coding style guide sections: naming conventions, formatting, comments, file structure, best practices.
Show keyboard layouts for QWERTY, AZERTY, QWERTZ, and Dvorak with visual keyboard display
Upload CSV, pivot data by rows/columns/values. Group by, aggregate (sum/count/avg). Interactive table.
Normalize data using Min-Max, Z-score, decimal scaling, log transform. Compare original vs normalized. Download.
Reference of common I2C device addresses: sensors, displays, EEPROMs, RTCs. Conflict detection for project planning.
Pin reference for Arduino Uno/Nano/Mega: digital, analog, PWM, SPI, I2C, interrupt-capable pins. Visual pinout.
GPIO pin reference for Raspberry Pi: BCM/Board numbering, function, voltage limits. Visual pinout diagram.
Reference of SMD and through-hole component packages: sizes, footprints, comparison chart. SOT23, SOIC, QFN, etc.
Calculate subnets from IP and mask. Show network, broadcast, host range, wildcard. VLSM support. Subnet table.
Searchable database of well-known ports (0-1023) and common registered ports. Service name, protocol, description.
Calculate download/upload times from bandwidth. Convert Mbps to MB/s. Compare connection types.
Expand/compress IPv6 addresses. Validate format. Show address type (global, link-local, multicast). Prefix calculator.
Reference for WiFi channels: 2.4GHz (1-14) and 5GHz. Non-overlapping channels. Interference guide.
Reference of network diagram symbols: router, switch, firewall, server, cloud, endpoint. SVG icons with labels.
Reference table showing allowed downtime for 99% through 99.999% SLAs. Per year/month/week/day.
Calculate DNS TTL values. Convert between seconds and human-readable. Best practices by record type.
Plan home network: devices, bandwidth needs, router placement, access points. IP address allocation.
Design MQTT topic hierarchies for IoT: device/room/function naming conventions. Generate topic tree. Best practices.
Plan Home Assistant entities: device name, entity type, area, integration. Naming convention guide. YAML hints.