Developer Utilities
The daily-driver utilities you'd otherwise spend time Googling for. Regex testing, JWT decoding, cron scheduling, diff checking, config validation, CLI linting — all the tools that make engineering faster. No accounts, no ads, no data collection. Just open and use.
67 tools
CLI UX Linter
Audit your CLI --help output for discoverability, flag consistency, examples, and error guidance
AI CLI Generator
Generate Node or Python CLI scaffolds from OpenAPI with auth wiring, retries, pagination, and shell completion stubs
CSV Endpoint Builder
Turn CSV data into endpoint-ready mock responses, OpenAPI snippets, and production starter templates
OpenProse Flow Linter
Lint OpenProse flow graphs for unreachable stages, dangling edges, privileged paths, and approval gaps
Trace Context Validator
Validate W3C traceparent and tracestate headers for distributed tracing correctness and propagation safety
Retry & Idempotency Contract Builder
Generate endpoint-level retry and idempotency contracts with deterministic test vectors and rollout guidance
CSP & SRI Policy Builder
Build strict CSP header templates and SRI tag snippets for frontend script hardening and safer deployments
Regex Tester
Test and debug regular expressions with live matching, capture group extraction, plain-English explanations, and ReDoS vulnerability detection. Supports JavaScript, Python, and Go regex flavors.
Mermaid Diagram Viewer
Render Mermaid diagrams instantly — flowcharts, sequence diagrams, and more with SVG/PNG export
Docker Compose Validator
Validate Docker Compose YAML with structural checks, dependency validation, and common mistake detection
JWT Decoder & Inspector
Decode and inspect JSON Web Tokens — header, payload, claims, and expiration
OpenAPI / Swagger Preview
Paste an OpenAPI or Swagger spec and see interactive API documentation instantly
GitHub Actions YAML Builder
Build GitHub Actions workflows visually — templates for Node, Python, Docker, deployment, and matrix strategies
Cron Expression Builder
Build and validate cron expressions with human-readable schedule descriptions, next-run previews, timezone support, and a free REST API for automation workflows.
Text & Code Diff Checker
Compare text, JSON, and YAML with structured change detection for reviews, debugging, and CI pipelines
3-Way Diff & Merge Tool
3-way merge with conflict resolution — compare Base, Theirs, and Mine versions to resolve merge conflicts
Tailwind CSS Reference
Interactive Tailwind CSS cheat sheet with 500+ utilities — search, browse by category, view live previews, and copy class names
GraphQL Schema Viewer
Paste a GraphQL schema and explore types, fields, and relationships — no server needed, all client-side
API Header Builder & cURL Generator
Build HTTP requests visually and generate code for cURL, fetch, axios, and Python with headers, auth, and query params
JSONPath Tester
Test JSONPath expressions with real-time results — interactive JSON tree with click-to-path, syntax help, and examples
HTTP Status Code Reference
Interactive searchable reference for all HTTP status codes with descriptions and use cases
NDJSON/JSONL Viewer
Parse and view JSONL (newline-delimited JSON) with interactive table, filtering, sorting, and export
IP & Subnet Calculator
Calculate subnets, CIDR ranges, network addresses, and host counts for IPv4 with visual binary breakdown
SSH Config Generator
Generate SSH config files with jump hosts, port forwarding, and identity keys — visual editor with presets
Shell Command Explainer
Break down and explain shell commands with annotated syntax highlighting and dangerous pattern detection
YAML/JSON5 Config Validator
Validate YAML, JSON5, and JSON configs with instant error detection, linting, and format conversion
Webhook Payload Inspector
Analyze webhook payloads with formatted JSON view, HMAC signature verification, timestamp detection, and cURL reconstruction
JSON Sorter & Cleaner
Sort JSON keys, remove null values, deduplicate arrays, flatten nested objects — multiple operations in one tool
Glob Pattern Tester
Test glob patterns against file paths with real-time matching — supports gitignore, tsconfig, and shell syntax
API Response Mocker
Generate mock API responses for testing — get instant code for fetch, MSW, Express, curl, and Python without spinning up a server
chmod Calculator
Visual Unix permission calculator with bidirectional numeric and symbolic chmod conversion
Env File Manager
Parse, validate, edit, and convert .env files between JSON, YAML, Docker, and Shell formats
Cron Expression Tester
Test cron expressions and see next run times in your timezone. Generate cron from natural language like 'every Monday at 9am'. Free, private, no signup.
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes for text or files
ENV File Validator
Validate .env files against .env.example — catch missing variables, empty values, and type mismatches
Environment Variable Generator
Generate .env files from Docker Compose, Kubernetes configs, or framework presets. Create documented environment variable templates instantly.
System Design Simulator
Visual drag-and-drop system architecture builder with components, connections, templates, and export — perfect for interview prep
Extension Guard
Scan Chrome extension permissions for security risks with risk scoring, dangerous combination detection, and plain-English explanations
URL Metadata Extractor
Extract OG tags, canonical URLs, meta descriptions, and JSON-LD from pasted HTML
Website Tech Stack Detector
Detect website frameworks and platforms from pasted HTML, headers, and script URLs
RSS Feed Validator
Validate RSS/Atom XML and preview feed entries with parser diagnostics
DNS Lookup Parser
Parse dig and nslookup output into structured DNS record views
HTTP Header Inspector
Inspect HTTP response headers for security, caching, and CORS posture
SSL Certificate Checker
Parse certificate text and check issuer, SANs, and expiry risk
OpenAPI Changelog Generator
Generate endpoint-level changelogs by diffing two OpenAPI specs
Webhook Signature Verifier
Verify webhook signatures and inspect payload integrity before processing
.gitignore Generator
Generate stack-aware .gitignore templates for modern projects
Package.json Generator
Generate package.json scaffolds for apps and libraries
License Compatibility Checker
Check whether open source licenses are compatible and get recommended outbound licenses
Semver Calculator
Compare semantic versions and test range expressions
Dockerfile Generator
Generate safer Dockerfile templates for Node, Python, and Go
CORS Debugger
Analyze CORS failures and output concrete server-side fixes
API Key Generator
Generate secure, format-aware API keys and tokens for local development, testing, and CI pipelines. Supports custom lengths, prefixes, and character sets.
Regex Explainer
Explain regex matches, groups, and behavior interactively
JSON Patch Builder
Build RFC 6902 patch arrays from source and target JSON
ENV Template Generator
Generate structured .env templates and environment docs
GraphQL Query Builder
Build GraphQL queries and mutations from field and variable inputs
Validation Schema Generator
Generate validation schemas from representative JSON examples
Rate Limit Calculator
Calculate allowed throughput and headroom for API quotas
OAuth Playground
Generate OAuth authorization URLs and token exchange requests
Nginx Config Converter
Convert and generate Nginx configuration patterns
Color Contrast Checker
Check WCAG 2.1 color contrast ratios between foreground and background colors. Shows AA/AAA pass/fail for normal and large text.
CSS Specificity Calculator
Calculate and visualize CSS selector specificity. Paste selectors to see specificity scores, compare multiple selectors, and understand which styles win.
Basic Auth Encoder / Decoder
Encode and decode HTTP Basic Authentication credentials. Generate the Authorization header or curl flag from username and password, or decode a token back to plaintext.
HTTP Cookie Builder
Build and validate Set-Cookie headers interactively. Configure all cookie attributes — Secure, HttpOnly, SameSite, Path, Domain, Expires, Max-Age, Partitioned.
Word & Character Counter
Count words, characters, sentences, paragraphs, and lines. Get instant reading time and speaking time estimates, plus top word frequency analysis.
.env Security Scanner
Detect exposed API keys, high-entropy secrets, and insecure defaults in .env files. Recognizes 40+ key formats from OpenAI, AWS, Stripe, GitHub, and more.
Category facts
This category currently contains 67 tools in Dev Tools. For machine-readable discovery, see /api/tools-by-category.json.
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