# Simple Dev Tools > Free, privacy-first developer utilities that run entirely in the browser. No signup, no ads, no server-side processing — input is never uploaded, logged, or stored. 47 tools across 9 categories. For the complete inlined content of every tool (full descriptions + FAQs) in one file, see https://simpledevtools.org/llms-full.txt — useful for answering questions about any tool without further crawling. ## JSON - [JSON Validator](https://simpledevtools.org/tools/json-validator): Validate JSON syntax and catch errors instantly. - [JSON to CSV Converter](https://simpledevtools.org/tools/json-to-csv): Convert a JSON array into a CSV file. - [CSV to JSON Converter](https://simpledevtools.org/tools/csv-to-json): Convert a CSV file into JSON. - [JSON to YAML Converter](https://simpledevtools.org/tools/json-to-yaml): Convert JSON into YAML format. - [YAML to JSON Converter](https://simpledevtools.org/tools/yaml-to-json): Convert YAML into JSON format. - [JSON Diff Checker](https://simpledevtools.org/tools/json-diff): Compare two JSON documents and see what changed. - [JSON Minifier](https://simpledevtools.org/tools/json-minifier): Minify JSON by stripping whitespace. ## Security - [JWT Decoder](https://simpledevtools.org/tools/jwt-decoder): Decode and inspect JWT tokens instantly. - [Password Generator](https://simpledevtools.org/tools/password-generator): Generate strong, random passwords. - [Certificate Decoder](https://simpledevtools.org/tools/certificate-decoder): Decode X.509 certificates into readable fields. - [Hash Generator](https://simpledevtools.org/tools/hash-generator): Generate MD5, SHA-1, SHA-256, and SHA-512 hashes. - [Bcrypt Hash Generator](https://simpledevtools.org/tools/bcrypt-generator): Generate and verify bcrypt password hashes. - [HMAC Generator](https://simpledevtools.org/tools/hmac-generator): Generate HMAC signatures with SHA-256/SHA-512. - [Password Strength Checker](https://simpledevtools.org/tools/password-entropy-checker): Estimate password strength and entropy. - [PEM to DER Converter](https://simpledevtools.org/tools/pem-to-der): Convert PEM-encoded certificates to DER format. ## Encoding - [Base64 Encoder/Decoder](https://simpledevtools.org/tools/base64): Encode or decode Base64 strings. - [URL Encoder/Decoder](https://simpledevtools.org/tools/url-encoder): Encode or decode URL components. ## Text - [Regex Tester](https://simpledevtools.org/tools/regex-tester): Test and debug regular expressions live. - [Text Diff Checker](https://simpledevtools.org/tools/text-diff): Compare two blocks of text and highlight differences. - [Markdown to HTML Converter](https://simpledevtools.org/tools/markdown-to-html): Convert Markdown into clean HTML. - [Case Converter](https://simpledevtools.org/tools/case-converter): Convert text between camelCase, snake_case, kebab-case, and more. - [Word & Character Counter](https://simpledevtools.org/tools/word-counter): Count words, characters, and reading time instantly. - [Slug Generator](https://simpledevtools.org/tools/slug-generator): Convert text into a clean, URL-safe slug. - [HTML Entity Encoder/Decoder](https://simpledevtools.org/tools/html-entity-encoder): Encode or decode HTML entities. - [Lorem Ipsum Generator](https://simpledevtools.org/tools/lorem-ipsum-generator): Generate placeholder text for mockups and layouts. ## Generators - [UUID Generator](https://simpledevtools.org/tools/uuid-generator): Generate v4 UUIDs instantly. - [NanoID Generator](https://simpledevtools.org/tools/nanoid-generator): Generate compact, URL-safe unique IDs. - [ULID Generator](https://simpledevtools.org/tools/ulid-generator): Generate sortable, timestamp-based ULIDs. - [QR Code Generator](https://simpledevtools.org/tools/qr-code-generator): Generate a QR code from text or a URL. - [Unix Timestamp Converter](https://simpledevtools.org/tools/timestamp-converter): Convert between Unix timestamps and human-readable dates. ## AI / LLM - [LLM Token Counter](https://simpledevtools.org/tools/token-counter): Count tokens for GPT, Claude, and other LLMs. - [OpenAI Pricing Calculator](https://simpledevtools.org/tools/openai-pricing-calculator): Estimate OpenAI API costs by token usage. - [Context Window Calculator](https://simpledevtools.org/tools/context-window-calculator): Check how much of a model's context window you're using. ## DevOps - [Docker Compose to Kubernetes Converter](https://simpledevtools.org/tools/docker-compose-to-kubernetes): Convert docker-compose.yml into Kubernetes manifests. - [Kubernetes YAML Validator](https://simpledevtools.org/tools/k8s-yaml-validator): Validate Kubernetes manifest YAML syntax and structure. - [Cron Expression Parser](https://simpledevtools.org/tools/cron-parser): Decode cron expressions into human-readable schedules. - [Dockerfile Linter](https://simpledevtools.org/tools/dockerfile-linter): Lint a Dockerfile for common issues and best practices. - [Helm Values Generator](https://simpledevtools.org/tools/helm-values-generator): Generate a values.yaml scaffold for Helm charts. - [.env to Docker Compose Converter](https://simpledevtools.org/tools/env-to-docker-compose): Convert a .env file into docker-compose environment config. ## API - [cURL Command Builder](https://simpledevtools.org/tools/curl-builder): Build cURL commands from a simple form. - [HTTP Header Analyzer](https://simpledevtools.org/tools/http-header-analyzer): Inspect and explain HTTP response headers. - [CIDR / Subnet Calculator](https://simpledevtools.org/tools/cidr-calculator): Calculate subnet ranges from CIDR notation. - [User-Agent Parser](https://simpledevtools.org/tools/user-agent-parser): Parse a User-Agent string into browser, OS, and device info. - [GraphQL Query Formatter](https://simpledevtools.org/tools/graphql-formatter): Format and beautify GraphQL queries. ## Design - [Color Converter](https://simpledevtools.org/tools/color-converter): Convert colors between HEX, RGB, and HSL. - [CSS Gradient Generator](https://simpledevtools.org/tools/css-gradient-generator): Visually build CSS linear and radial gradients. - [Color Contrast Checker](https://simpledevtools.org/tools/contrast-checker): Check color contrast against WCAG accessibility guidelines. ## Docs - [About](https://simpledevtools.org/about): Who builds this and why it runs entirely client-side. - [Blog](https://simpledevtools.org/blog): Guides and deep-dives on the tools and the problems they solve. - [Privacy](https://simpledevtools.org/privacy): No data collection policy — verifiable via the network tab. - [Terms](https://simpledevtools.org/terms): Terms of service. - [Terms](https://simpledevtools.org/changelog): Changelog ## Optional - [Sitemap](https://simpledevtools.org/sitemap.xml): Full URL list for crawling. - [Full content](https://simpledevtools.org/llms-full.txt): Every tool's complete description and FAQ inlined.