Developer toolkit
Everyday utilities developers reach for — JSON, encoding, regex, SQL, timestamps, and more. Free tools run entirely in your browser.
Diagrams & design
Mermaid Studio
FreeLive Mermaid editor for flowcharts, sequence, ER, class, state, gantt, and mindmaps.
Architecture Canvas
FreeVisual cloud architecture editor with AWS, GCP, and Azure component libraries.
Sequence Builder
FreeBuild sequence diagrams from actors and messages, then export Mermaid.
ER Diagram Builder
FreeModel entities, fields, and relationships into Mermaid ER diagrams.
ASCII Diagram
FreeGenerate box-and-arrow ASCII diagrams for docs and READMEs.
JSON & data
JSON Formatter
FreeBeautify, minify, and validate JSON with one click.
JSON Comparator
FreeCompare two JSON objects and visualize differences.
YAML ↔ JSON
FreeConvert between YAML and JSON for configs, K8s, and CI files.
CSV ↔ JSON
FreeConvert CSV tables to JSON arrays and back with delimiter detection.
JSONPath Query
FreeQuery JSON with path expressions like $.items[*].id.
Encode / decode
Base64 Encode/Decode
FreeEncode text to Base64 or decode Base64 back to text.
URL Encode/Decode
FreePercent-encode and decode URLs and query strings.
HTML Entity Encoder
FreeEscape and unescape HTML entities safely.
XML / HTML Formatter
FreeFormat, minify, and check well-formed XML or HTML markup.
Number Base Converter
FreeConvert numbers between binary, octal, decimal, and hex.
Color Converter
FreePick colors and convert between HEX, RGB, and HSL.
QR Code Generator
FreeCreate QR codes from text or URLs and download as PNG.
Text & format
Markdown Preview
FreeWrite Markdown with a live GitHub-flavored preview.
Regex Tester
FreeTest regular expressions with live match highlighting.
Text Diff
FreeCompare two text blocks and highlight line differences.
Case Converter
FreeConvert text between camelCase, snake_case, kebab-case, and more.
CodeVault
FreeStore, organize, and share code snippets with tagging.
Security
JWT Reader/Decoder
FreeDecode and analyze JSON Web Tokens to view their contents.
JWT Verifier
FreeVerify JWT signatures with HMAC secrets or RSA public keys.
JWT Signer
FreeSign JWTs locally with HS256, HS384, or HS512 secrets.
Hash Calculator
FreeGenerate SHA-1, SHA-256, SHA-384, and SHA-512 hashes for text.
HMAC & AES
FreeCompute HMAC digests and encrypt/decrypt with AES-GCM in the browser.
UUID / GUID Generator
FreeGenerate UUID v1, v4, and v7 identifiers for your applications.
Password Generator
FreeGenerate strong passwords and secrets with configurable character sets.
Time
Query & APIs
SQL Formatter
FreeFormat and beautify SQL queries for readability.
API Tester
FreeTest REST APIs with requests, headers, environments, and responses.
GraphQL Playground
FreeRun GraphQL queries against any endpoint with variables and headers.
cURL / OpenAPI Importer
FreeParse cURL commands or OpenAPI ops into ready-to-send requests.