Free Online Developer Tools

All tools

• UUID / ULID Generator — Generate UUID v4 and ULID identifiers in your browser.
• Hash Text — Compute SHA-1, SHA-256, or SHA-512 digests of any text.
• HMAC Generator — Generate HMAC signatures with SHA-256 or SHA-512.
• JWT Decoder — Decode JWT header and payload. Does not verify signatures.
• Password / Token Generator — Generate strong random passwords and API tokens.
• Bcrypt Hash & Verify — Hash passwords with bcrypt and verify candidates client-side.
• Base64 Encode / Decode — Convert text to and from Base64 encoding.
• URL Encode / Decode — Percent-encode and decode URL components safely.
• HTML Entities — Encode and decode HTML entities for safe markup.
• Case Converter — Convert between camelCase, snake_case, kebab-case, PascalCase, and Title Case.
• JSON ↔ YAML — Convert between JSON and YAML, format, or minify JSON.
• Number Base Converter — Convert integers between binary, octal, decimal, and hexadecimal.
• URL Parser — Break a URL into protocol, host, path, query, and hash parts.
• Regex Tester — Test JavaScript regular expressions against sample text.
• Text Diff — Compare two texts and highlight line-level differences.
• Lorem Ipsum Generator — Generate placeholder paragraphs, sentences, or words.
• Slugify — Turn any string into a URL-safe slug.
• Cron Explainer — Explain cron expressions and preview upcoming run times.
• Unix Timestamp — Convert between Unix timestamps and human-readable dates.
• Chmod Calculator — Convert between symbolic and octal Unix file permissions.
• JSON Diff — Compare two JSON objects and list structural differences.
• SQL Formatter — Format or minify SQL queries for readability.
• Color Converter — Convert colors between HEX, RGB, and HSL.
• XML ↔ JSON — Convert between XML and JSON in your browser.
• QR Code Generator — Generate a QR code from text or a URL and download it as PNG.
• Markdown → HTML — Convert Markdown to HTML with a live preview.
• IPv4 Subnet Calculator — Parse CIDR blocks and show network, mask, and host ranges.
• TOTP / OTP Generator — Generate and verify time-based one-time passwords (TOTP) client-side.
• Meta Tag Generator — Generate Open Graph and basic social HTML meta tags.
• Docker Run → Compose — Turn a docker run command into a docker-compose YAML sketch.
• AI Token Estimator — Rough token and cost estimate for prompts — napkin math for LLM calls.
• OpenAPI → Snippet — Paste an OpenAPI path operation and get curl or fetch snippets.
• AWS Cost Sketch — Quick napkin estimate for EC2, S3 storage, and egress (approximate).
• AES Encrypt / Decrypt — Encrypt and decrypt text with AES-256-GCM (passphrase + PBKDF2) in the browser.
• Password Strength — Analyse password strength, entropy, and a rough crack-time sketch.
• RSA Key Pair Generator — Generate RSA-OAEP public and private PEM keys with Web Crypto.
• Basic Auth Generator — Build a Base64 Basic Authorization header from username and password.
• TOML ↔ JSON / YAML — Convert between TOML, JSON, and YAML.
• JSON ↔ CSV — Convert arrays of objects to CSV and back.
• List Converter — Prefix, suffix, sort, reverse, lowercase, or truncate list lines.
• HTTP Status Codes — Look up common HTTP status codes and short meanings.
• User-Agent Parser — Parse browser, OS, and device hints from a User-Agent string.
• MIME Types — Map file extensions to MIME types and back.
• Keycode Info — Inspect key, code, and modifier flags for any pressed key.
• Device Information — Show screen, viewport, locale, and browser capability details.
• IPv4 Address Converter — Convert IPv4 between dotted, decimal, hex, binary, and IPv6-mapped forms.
• IPv4 Range Expander — Compute address count and a covering CIDR for an IPv4 range.
• MAC Address Generator — Generate random locally administered MAC addresses.
• IPv6 ULA Generator — Generate RFC 4193 Unique Local IPv6 Addresses for private networks.
• Random Port Generator — Generate random TCP/UDP ports outside the well-known range.
• Text Statistics — Count characters, words, lines, paragraphs, and UTF-8 bytes.
• String Obfuscator — Mask the middle of tokens or secrets for safer sharing.
• Phone Parser — Parse, validate, and format phone numbers (E.164 and more).
• IBAN Validator — Validate IBANs and show country code and BBAN parts.
• JWT Builder — Edit JWT header/payload, set expiry, and optionally HS256-sign in the browser.
• JSONPath Tester — Query nested JSON with JSONPath expressions.
• cURL → fetch / HTTPie — Convert curl commands into JavaScript fetch or HTTPie.
• GraphQL Formatter — Format or minify GraphQL queries and pretty-print variables.
• Env Diff / Merge — Diff and merge .env files; override wins.
• Semver Bump & Compare — Bump major/minor/patch and check version ranges.
• .gitignore Generator — Generate .gitignore from Node, Next, Python, Docker, and more.
• Certificate Inspector — Inspect X.509 certificate PEM: subject, issuer, dates, thumbprint.
• Webhook HMAC Signer — Sign and verify webhook payloads with HMAC (Stripe/GitHub-style).
• Unicode / IDN — Inspect Unicode code points and convert domains with IDNA.
• OpenAPI → TypeScript — Generate TypeScript interfaces from OpenAPI component schemas.
• JSON Schema Validator — Validate a JSON instance against a JSON Schema.
• LLM Prompt Linter — Heuristic lint for system prompts: tokens, PII patterns, safety cues.
• AWS ARN Parser — Split an AWS ARN into partition, service, region, account, and resource.
• Terraform / CFN Snippets — Sketch Terraform tags, S3, and IAM policy snippets (review before apply).
• API Latency Napkin — Rough per-request latency and worker busy-fraction estimate.
• CORS Header Debugger — Paste request/response headers and diagnose CORS mismatches.
• CSP Builder — Build a Content-Security-Policy header from common directives.