# Kevinbkdev Toolbox

> Free, privacy-first developer tools that run entirely in your browser: JSON, JWT, Base64, regex, cron, UUID, EVM calldata and more. Nothing is uploaded.

141 small, single-purpose developer tools by [Kevinbkdev](https://kevinbkdev.vercel.app/me). Every tool runs entirely client-side in the browser: input is never uploaded, there is no sign-up, and everything is free. Part of the [Kevinbkdev blog](https://kevinbkdev.vercel.app) (Backend, Blockchain, DevOps).

- Catalog: https://kevinbkdev.vercel.app/tools
- Sitemap: https://kevinbkdev.vercel.app/tools/sitemap.xml
- Full text (descriptions, use cases, FAQs): https://kevinbkdev.vercel.app/tools/llms-full.txt

## Data & Database

- [JSON Formatter and Validator Online](https://kevinbkdev.vercel.app/tools/json-formatter): Format, validate, and minify JSON directly in your browser.
- [JSON Minifier: Compress JSON Online](https://kevinbkdev.vercel.app/tools/json-minify): Minify and compress JSON data by stripping unnecessary whitespace and line breaks.
- [SQL Formatter and Beautifier Online](https://kevinbkdev.vercel.app/tools/sql-prettify): Format, beautify, and indent SQL queries with customizable keyword casing and spacing.
- [JSONPath Tester and Evaluator Online](https://kevinbkdev.vercel.app/tools/jsonpath-playground): Query JSON documents with JSONPath expressions and inspect matched values and paths.

## Encode & Security

- [Base64 Encode & Decode Online (UTF-8)](https://kevinbkdev.vercel.app/tools/base64): Encode UTF-8 text to Base64 or decode Base64 locally.
- [File to Base64 & Data URL Converter](https://kevinbkdev.vercel.app/tools/base64-file-converter): Convert files, images, or text into Base64 and Data URLs, or decode Base64 data URLs back to raw bytes locally.
- [Bcrypt Hash Generator & Checker](https://kevinbkdev.vercel.app/tools/bcrypt): Hash and compare text string using bcrypt. Bcrypt is a password-hashing function based on the Blowfish cipher.
- [Hash Generator: MD5, SHA-1, SHA-256, SHA-512](https://kevinbkdev.vercel.app/tools/hash-text): Hash a text string using MD5, SHA-1, SHA-2 (224/256/384/512), SHA3-256, SHA3-512, Keccak-256 or RIPEMD-160.
- [HMAC Generator: HMAC-SHA256 Online](https://kevinbkdev.vercel.app/tools/hmac-generator): Computes a hash-based message authentication code (HMAC) using a secret key and a cryptographic hash function.
- [HTML Entity Encoder & Decoder](https://kevinbkdev.vercel.app/tools/html-entities): Encode text as HTML entities or decode entities back into readable text.
- [String Obfuscator: Mask Secrets, Tokens & IBANs](https://kevinbkdev.vercel.app/tools/string-obfuscator): Obfuscate a string (like a secret, an IBAN, or a token) to make it shareable and identifiable without revealing its content.
- [AES Text Encryption: Encrypt & Decrypt Online](https://kevinbkdev.vercel.app/tools/encryption): Encrypt and decrypt plaintext with AES-GCM or AES-CBC and PBKDF2 passphrase derivation locally.
- [Text to Binary Converter (and Binary to Text)](https://kevinbkdev.vercel.app/tools/text-to-binary): Encode text as eight-bit binary or decode binary back into text locally.
- [Text to Unicode Converter: U+ Code Points](https://kevinbkdev.vercel.app/tools/text-to-unicode): Encode text as deterministic U+ code points or decode them back locally.
- [URL Encode & Decode Online (Percent-Encoding)](https://kevinbkdev.vercel.app/tools/url-encoder): Encode or decode URL components without leaving your browser.
- [Kubernetes Secret Decoder & Base64 Encoder](https://kevinbkdev.vercel.app/tools/k8s-secret-converter): Encode or decode every data field of a Kubernetes Secret manifest between plain text and Base64.

## Inspect & Analyze

- [Device Info: Screen Resolution, Pixel Ratio, GPU](https://kevinbkdev.vercel.app/tools/device-information): Inspect device specifications, screen resolution, pixel ratio, platform, and browser capabilities locally.
- [HTML Preview Online - Sandboxed HTML Renderer](https://kevinbkdev.vercel.app/tools/html-preview): Render a user-provided HTML fragment in an isolated, sandboxed preview while exposing the source and safety boundaries.
- [JWT Decoder - Decode JSON Web Token Online](https://kevinbkdev.vercel.app/tools/jwt-parser): Parse and decode JSON Web Tokens (JWT) to inspect headers, payload claims, and expiration locally.
- [JavaScript Keycode Finder - event.key & event.code](https://kevinbkdev.vercel.app/tools/keycode-info): Discover JavaScript key codes, code identifiers, locations, and keyboard event properties in real time.
- [Password Strength Checker - Entropy & Crack Time](https://kevinbkdev.vercel.app/tools/password-strength-analyser): Analyse password strength, Shannon entropy, and crack time estimates locally.
- [Word & Character Counter with Reading Time](https://kevinbkdev.vercel.app/tools/text-statistics): Count characters, words, lines, and UTF-8 bytes in a text locally.
- [User Agent Parser - Detect Browser, OS & Device](https://kevinbkdev.vercel.app/tools/user-agent-parser): Parse and analyze User-Agent strings to detect browser, OS, device, engine, and architecture locally.
- [UUID Decoder - Version, Timestamp, ULID Parser](https://kevinbkdev.vercel.app/tools/uuid-ulid-decoder): Inspect UUID and ULID versions, timestamps, variants, and canonical representations.
- [X.509 Certificate Decoder - PEM & CSR Viewer](https://kevinbkdev.vercel.app/tools/x509-certificate-decoder): Decode PEM certificates and CSRs: subject, issuer, SANs, validity, key and fingerprints.

## Convert

- [Number Base Converter: Binary, Hex, Octal, Decimal](https://kevinbkdev.vercel.app/tools/base-converter): Synchronize integers across every base from 2 through 36.
- [Color Converter: HEX to RGB, HSL, HWB, CMYK](https://kevinbkdev.vercel.app/tools/color-converter): Synchronize colors between normalized hex, RGB, and HSL representations locally.
- [Docker Run to Docker Compose Converter](https://kevinbkdev.vercel.app/tools/docker-run-to-docker-compose-converter): Convert CLI docker run commands into structured, clean docker-compose.yml files.
- [JSON to CSV Converter Online](https://kevinbkdev.vercel.app/tools/json-to-csv): Convert JSON arrays and objects into formatted CSV or TSV with automatic header detection.
- [JSON to TOML Converter Online](https://kevinbkdev.vercel.app/tools/json-to-toml): Convert JSON configuration and data structures directly into valid TOML format.
- [JSON to XML Converter Online](https://kevinbkdev.vercel.app/tools/json-to-xml): Convert JSON data into clean, well-formatted XML locally.
- [JSON to YAML Converter Online](https://kevinbkdev.vercel.app/tools/json-to-yaml-converter): Convert JSON documents into clean, human-readable YAML with configurable spacing and quoting options.
- [Markdown to HTML Converter with Live Preview](https://kevinbkdev.vercel.app/tools/markdown-to-html): Convert Markdown syntax into clean, sanitized HTML markup with rendered live preview.
- [Roman Numeral Converter: Numbers to Roman and Back](https://kevinbkdev.vercel.app/tools/roman-numeral-converter): Convert Roman numerals to numbers and numbers to Roman numerals.
- [Temperature Converter: Celsius, Fahrenheit, Kelvin](https://kevinbkdev.vercel.app/tools/temperature-converter): Degrees temperature conversions for Kelvin, Celsius, Fahrenheit, Rankine, Delisle, Newton, Réaumur, and Rømer.
- [Text to NATO Phonetic Alphabet Converter](https://kevinbkdev.vercel.app/tools/text-to-nato-alphabet): Translate text into NATO phonetic alphabet words for clear oral spelling.
- [TOML to JSON Converter Online](https://kevinbkdev.vercel.app/tools/toml-to-json): Parse TOML documents and convert sections, tables, and key-value pairs into valid JSON.
- [TOML to YAML Converter Online](https://kevinbkdev.vercel.app/tools/toml-to-yaml): Convert TOML configuration documents into clean, human-readable YAML.
- [XML to JSON Converter Online](https://kevinbkdev.vercel.app/tools/xml-to-json): Parse and convert XML data into clean JSON format locally.
- [YAML to JSON Converter Online](https://kevinbkdev.vercel.app/tools/yaml-to-json-converter): Convert YAML configuration and data structures into valid, formatted JSON documents.
- [YAML to TOML Converter Online](https://kevinbkdev.vercel.app/tools/yaml-to-toml): Convert YAML data structures, dictionaries, and arrays into valid TOML documents.
- [YAML to XML Converter Online](https://kevinbkdev.vercel.app/tools/yaml-to-xml): Convert YAML mappings, nested objects, arrays, and scalars into structured XML locally.
- [.env Converter: .env to JSON, YAML, ConfigMap](https://kevinbkdev.vercel.app/tools/env-converter): Convert between .env files, JSON and YAML, with validation of keys and quoting.
- [CSV to JSON Converter Online](https://kevinbkdev.vercel.app/tools/csv-to-json): Convert CSV or TSV into JSON arrays or objects with header and type detection.

## Date, Time & Math

- [Online Stopwatch with Laps](https://kevinbkdev.vercel.app/tools/chronometer): High-precision digital stopwatch with split lap tracking, fastest/slowest lap calculation, and elapsed time diagnostics.
- [Unix Timestamp Converter: Epoch to Date](https://kevinbkdev.vercel.app/tools/date-converter): Convert date and time between ISO, UTC, Unix timestamps, and calendar metadata locally.
- [ETA Calculator: Time Remaining and Completion](https://kevinbkdev.vercel.app/tools/eta-calculator): Calculate remaining transfer or process time, percentage progress, and estimated completion date.
- [Online Math Expression Calculator](https://kevinbkdev.vercel.app/tools/math-evaluator): Evaluate arithmetic and scientific math expressions with trigonometric, logarithmic, and power functions.
- [Percentage Calculator: Percent of, Change, Ratio](https://kevinbkdev.vercel.app/tools/percentage-calculator): Calculate a percentage of a value, percentage change, or a value from a percentage.

## Generate

- [ASCII Art Text Generator (FIGlet Fonts)](https://kevinbkdev.vercel.app/tools/ascii-text-drawer): Create stylized ASCII art banners and text with multiple fonts and styles locally.
- [Basic Auth Header Generator (Base64)](https://kevinbkdev.vercel.app/tools/basic-auth-generator): Generate a base64 basic auth header from a username and password.
- [BIP39 Mnemonic Generator and Seed Calculator](https://kevinbkdev.vercel.app/tools/bip39-generator): Generate a BIP39 passphrase from an existing or random mnemonic, or get the mnemonic from the passphrase.
- [Cron Expression Generator and Explainer](https://kevinbkdev.vercel.app/tools/crontab-generator): Validate, build, and explain cron expressions with human-readable descriptions and next run schedules.
- [IPv6 ULA Generator (RFC 4193, fd00::/8)](https://kevinbkdev.vercel.app/tools/ipv6-ula-generator): Generate RFC 4193 compliant IPv6 Unique Local Addresses (ULA) and /64 subnets.
- [Lorem Ipsum Generator (Paragraphs, Words)](https://kevinbkdev.vercel.app/tools/lorem-ipsum-generator): Generate placeholder text, sentences, and paragraphs locally.
- [Random MAC Address Generator](https://kevinbkdev.vercel.app/tools/mac-address-generator): Generate random MAC addresses with custom prefixes, casing, and separator formats.
- [Numeronym Generator (i18n, k8s, a11y)](https://kevinbkdev.vercel.app/tools/numeronym-generator): Generate numeronyms (like i18n, k8s, a11y) from words and sentences locally.
- [Open Graph Meta Tag Generator (+ Twitter Cards)](https://kevinbkdev.vercel.app/tools/og-meta-generator): Generate Open Graph and Twitter/X HTML meta tags for rich social media sharing previews.
- [TOTP / HOTP Code Generator and Validator](https://kevinbkdev.vercel.app/tools/otp-generator): Generate and validate time-based (TOTP) and counter-based (HOTP) one-time passwords locally.
- [QR Code Generator (PNG and SVG Download)](https://kevinbkdev.vercel.app/tools/qrcode-generator): Generate a QR code for a URL or text with custom colors, size, margin and error correction, and download it as PNG or SVG.
- [Random Port Number Generator](https://kevinbkdev.vercel.app/tools/random-port-generator): Generate random unprivileged network port numbers (1024-65535) locally.
- [RSA Key Pair Generator (PEM, 2048/4096)](https://kevinbkdev.vercel.app/tools/rsa-key-pair-generator): Generate random RSA private and public key pairs in standard PEM format locally.
- [SVG Placeholder Image Generator](https://kevinbkdev.vercel.app/tools/svg-placeholder-generator): Generate customizable SVG image placeholders with custom dimensions, colors, and text.
- [Random Token and String Generator (Secure)](https://kevinbkdev.vercel.app/tools/token-generator): Generate cryptographically secure random tokens and strings with custom character sets locally.
- [ULID Generator Online (Sortable Unique IDs)](https://kevinbkdev.vercel.app/tools/ulid-generator): Generate Universally Unique Lexicographically Sortable Identifiers (ULID) locally.
- [UUID Generator Online (v4, v7, v1)](https://kevinbkdev.vercel.app/tools/uuid-generator): Generate UUIDs (v4 random, v7 time-ordered, or v1) in bulk, locally in your browser.
- [WiFi QR Code Generator (WPA/WPA2/WEP)](https://kevinbkdev.vercel.app/tools/wifi-qrcode-generator): Generate and download QR codes for quick connections to WiFi networks.
- [SSH Key Generator (Ed25519, OpenSSH Format)](https://kevinbkdev.vercel.app/tools/ssh-key-generator): Generate Ed25519 SSH key pairs in OpenSSH format with fingerprints.
- [Markdown Table Generator (from CSV or Excel)](https://kevinbkdev.vercel.app/tools/markdown-table-generator): Build Markdown tables in an editable grid or convert CSV and pasted spreadsheet data.
- [.gitignore Generator (Node, Python, Go, ...)](https://kevinbkdev.vercel.app/tools/gitignore-generator): Compose a .gitignore from templates for languages, frameworks, editors and operating systems.

## Test & Debug

- [JavaScript Benchmark - Compare Code Speed Online](https://kevinbkdev.vercel.app/tools/benchmark-builder): Compare JavaScript performance, execution speed, and ops/sec between multiple code snippets directly in your browser.
- [IBAN Validator & Checker - Parse Bank Details](https://kevinbkdev.vercel.app/tools/iban-validator-and-parser): Validate and parse International Bank Account Numbers (IBAN), verify ISO 7064 checksums, and detect QR-IBANs.
- [JSON Diff - Compare Two JSON Objects Online](https://kevinbkdev.vercel.app/tools/json-diff): Compare two JSON objects or arrays and compute deep structural differences and changes.
- [Regex Tester - JavaScript Regular Expressions](https://kevinbkdev.vercel.app/tools/regex-tester): Test regular expressions with flags, match highlighting, capture group extraction, and replacement preview.
- [Text Diff Checker - Compare Text Online](https://kevinbkdev.vercel.app/tools/text-diff): Compare two text blocks and compute line-by-line additions, deletions, and unified diff output.

## Code & Developer

- [Git Cheat Sheet (Commands with Examples)](https://kevinbkdev.vercel.app/tools/git-memo): Searchable reference guide for essential and advanced Git commands with explanations and examples.
- [Claude Code Cheat Sheet (Commands, Shortcuts & API)](https://kevinbkdev.vercel.app/tools/claude-memo): Searchable reference for Claude Code commands, shortcuts, settings, hooks and MCP, plus Claude API essentials.
- [Regex Cheat Sheet (JavaScript Regular Expressions)](https://kevinbkdev.vercel.app/tools/regex-memo): Searchable reference guide for regular expressions tokens, quantifiers, lookarounds, and common recipes.
- [cURL to Code Converter (fetch, Python, Go, PHP)](https://kevinbkdev.vercel.app/tools/curl-converter): Convert a cURL command into fetch, axios, Go net/http, Python requests or PHP cURL code.
- [JSON to TypeScript, Go Struct and Zod Converter](https://kevinbkdev.vercel.app/tools/json-to-types): Generate TypeScript interfaces, Go structs or Zod schemas from a JSON sample.
- [Semver Calculator and Range Checker (npm)](https://kevinbkdev.vercel.app/tools/semver-calculator): Compare semantic versions, test ranges like ^1.2.3 and ~1.2, and compute the next version.

## Transform

- [Escape / Unescape String: Backslash & Quotes](https://kevinbkdev.vercel.app/tools/backslash-escape): Escape or unescape backslashes, quotes, newlines, tabs, and control characters for source-safe strings.
- [Case Converter: camelCase, snake_case, kebab-case](https://kevinbkdev.vercel.app/tools/case-converter): Transform text between upper, lower, title, camel, snake, and kebab case.
- [CSS Beautifier & Minifier: Format CSS Online](https://kevinbkdev.vercel.app/tools/css-beautifier): Format or minify CSS rules, selectors, declarations, and at-rules locally.
- [Email Normalizer: Dedupe Gmail Dots & +Tags](https://kevinbkdev.vercel.app/tools/email-normalizer): Normalize and sanitize email addresses to a canonical form for deduplication and data cleaning.
- [ERB Formatter: Beautify Rails .html.erb Templates](https://kevinbkdev.vercel.app/tools/erb-beautifier): Format ERB templates while preserving embedded Ruby delimiters and HTML structure without executing code.
- [HTML Beautifier & Minifier: Format HTML Online](https://kevinbkdev.vercel.app/tools/html-beautifier): Format or minify HTML markup with predictable indentation and readable structure.
- [Online HTML WYSIWYG Editor: Rich Text to HTML](https://kevinbkdev.vercel.app/tools/html-wysiwyg-editor): Visual rich text HTML editor with styling toolbars, live preview, and sanitized markup export.
- [JavaScript Beautifier: Format & Minify JS](https://kevinbkdev.vercel.app/tools/javascript-beautifier): Format or minify JavaScript source code while preserving strings and comments safely without executing user code.
- [LESS Beautifier & Minifier: Format LESS Code](https://kevinbkdev.vercel.app/tools/less-beautifier): Format or minify LESS stylesheets while preserving variables, nesting, and mixins without compiling.
- [List Converter: Comma, Newline & Delimiter Lists](https://kevinbkdev.vercel.app/tools/list-converter): Convert delimited lists between common separators and count their items locally.
- [Phone Number Formatter & Validator: E.164](https://kevinbkdev.vercel.app/tools/phone-parser-and-formatter): Parse, validate, and convert international phone numbers into E.164, National, International, and RFC3966 formats.
- [SCSS Beautifier & Minifier: Format Sass Code](https://kevinbkdev.vercel.app/tools/scss-beautifier): Format or minify SCSS stylesheets while preserving variables, mixins, directives, and nesting without compiling.
- [Slugify: Convert Text to a URL Slug](https://kevinbkdev.vercel.app/tools/slugify-string): Convert text into a URL-, filename-, and ID-safe slug locally.
- [XML Formatter & Validator: Pretty Print XML](https://kevinbkdev.vercel.app/tools/xml-formatter): Format, indent, and prettify XML documents with customizable indent sizes and tag normalization.
- [YAML Formatter & Validator: Prettify YAML](https://kevinbkdev.vercel.app/tools/yaml-prettify): Format, validate, re-indent, and beautify YAML markup with optional key sorting.

## Web & Network

- [Country Codes & Flag Emoji (ISO 3166-1)](https://kevinbkdev.vercel.app/tools/country-flag-lookup): Search ISO 3166-1 country codes, names, flags, and Unicode sequences locally.
- [ISO 4217 Currency Codes, Symbols & Decimals](https://kevinbkdev.vercel.app/tools/currency-lookup): Search ISO 4217 currency codes, names, and symbols in a bundled local reference.
- [HTTP Status Codes List & Meanings](https://kevinbkdev.vercel.app/tools/http-status-codes): Searchable reference for common HTTP status codes, meanings, and response categories.
- [IP to Decimal, Hex & Binary Converter (IPv4)](https://kevinbkdev.vercel.app/tools/ipv4-address-converter): Convert IPv4 addresses between decimal, binary, hexadecimal, octal, and IPv6 representations.
- [IP Range to CIDR Converter (IPv4)](https://kevinbkdev.vercel.app/tools/ipv4-range-expander): Calculate minimal valid IPv4 CIDR blocks covering an IP address range.
- [CIDR / Subnet Calculator (IPv4)](https://kevinbkdev.vercel.app/tools/ipv4-subnet-calculator): Parse IPv4 CIDR blocks and calculate network range, subnet mask, usable host IPs, and broadcast address.
- [MAC Address Lookup - Find Vendor by OUI](https://kevinbkdev.vercel.app/tools/mac-address-lookup): Find the vendor and manufacturer of a device by its MAC address.
- [MIME Types List - File Extension to Content-Type](https://kevinbkdev.vercel.app/tools/mime-types): Searchable reference for common file extensions and MIME types with one-click copying.
- [Outlook Safe Links Decoder - Unwrap URLs](https://kevinbkdev.vercel.app/tools/safelink-decoder): Decode Outlook SafeLink and security wrapper links to reveal their destination URL.
- [URL Parser - Split URL & Query String Online](https://kevinbkdev.vercel.app/tools/url-parser): Parse an absolute URL into its protocol, host, path, query, and other components locally.
- [IPv6 Subnet Calculator - CIDR & Prefix](https://kevinbkdev.vercel.app/tools/ipv6-subnet-calculator): Parse IPv6 CIDR blocks: expanded and compressed forms, network range, address count and subnetting.
- [CIDR Overlap Checker - IPv4 & IPv6 Ranges](https://kevinbkdev.vercel.app/tools/cidr-overlap-checker): Detect overlapping or contained IPv4 and IPv6 CIDR ranges, e.g. across VPCs and subnets.

## Blockchain (EVM)

- [EVM Unit Converter: Wei, Gwei & Ether](https://kevinbkdev.vercel.app/tools/evm-unit-converter): Convert between Wei, Gwei, Ether and any token decimals with exact big-number precision.
- [Ethereum Calldata Decoder: Decode Input Data](https://kevinbkdev.vercel.app/tools/evm-input-data-decoder): Decode transaction calldata into the function name and typed arguments using an ABI or known selectors.
- [Ethereum Calldata Encoder: ABI-Encode Function Calls](https://kevinbkdev.vercel.app/tools/evm-input-data-encoder): Encode a function call and its arguments into ABI calldata from a signature or contract ABI.
- [Function Selector & Event Topic Calculator (Solidity)](https://kevinbkdev.vercel.app/tools/evm-method-id): Compute 4-byte function selectors and event topics from signatures, or look up common selectors.
- [EVM Bytecode Disassembler: Bytecode to Opcodes](https://kevinbkdev.vercel.app/tools/evm-bytecode-to-opcode): Disassemble EVM bytecode into opcodes with offsets, push data and Solidity metadata.
- [Hex to UTF-8 & bytes32 String Converter (Solidity)](https://kevinbkdev.vercel.app/tools/evm-utf8-converter): Convert between hex bytes, UTF-8 text and bytes32 strings for Solidity and calldata.
- [NFT tokenURI Base64 Decoder & Data URI Encoder](https://kevinbkdev.vercel.app/tools/evm-base64-converter): Convert between Base64 and hex bytes, e.g. for on-chain token URIs and data URIs.
- [JSON to Escaped String for Solidity & JS](https://kevinbkdev.vercel.app/tools/evm-json-serializer): Serialize JSON into an escaped single-line string literal for contracts and scripts, and back.
- [Solidity Standard JSON Input Viewer & Flattener](https://kevinbkdev.vercel.app/tools/solidity-json-simplifier): Split Solidity standard-JSON input into readable source files or flatten them into one.
- [Verify Ethereum Signature: personal_sign & EIP-712](https://kevinbkdev.vercel.app/tools/evm-verify-signature): Recover the signer of a personal_sign or EIP-712 typed-data signature and verify it against an address.
- [Solidity Contract Diff: Compare Two Versions](https://kevinbkdev.vercel.app/tools/evm-contract-diff): Compare two versions of a contract source side by side with line-level highlighting.
- [Ethereum Raw Transaction Decoder (Signed Tx Hex)](https://kevinbkdev.vercel.app/tools/evm-raw-tx-decoder): Decode a signed raw transaction: type, nonce, gas, value, calldata and recovered sender.
- [Ethereum Event Log Decoder: Topics & Data](https://kevinbkdev.vercel.app/tools/evm-event-log-decoder): Decode event log topics and data into the event name and typed arguments using an ABI or known events.
- [Solidity Revert Reason & Custom Error Decoder](https://kevinbkdev.vercel.app/tools/evm-revert-decoder): Decode revert data: Error(string), Panic codes and custom errors from an ABI or known signatures.
- [CREATE & CREATE2 Contract Address Calculator](https://kevinbkdev.vercel.app/tools/evm-contract-address-calculator): Precompute contract addresses from deployer and nonce (CREATE) or salt and init code hash (CREATE2).
- [Solidity Storage Slot Calculator: Mapping & Array](https://kevinbkdev.vercel.app/tools/evm-storage-slot-calculator): Compute storage slots for mappings, dynamic arrays, ERC-1967 proxy slots and ERC-7201 namespaces.
- [Merkle Tree Generator for Airdrops & Allowlists](https://kevinbkdev.vercel.app/tools/evm-merkle-tree): Build an OpenZeppelin-compatible Merkle tree for airdrops and allowlists, with root and per-leaf proofs.
- [ABI to Solidity Interface & TypeScript Types](https://kevinbkdev.vercel.app/tools/evm-abi-to-interface): Generate a Solidity interface or TypeScript types from a contract ABI.
- [EIP-55 Checksum Address & ENS Namehash Tool](https://kevinbkdev.vercel.app/tools/evm-checksum-address): Convert addresses to EIP-55 checksum form and compute ENS namehash and labelhash.
- [RLP Encoder & Decoder for Ethereum](https://kevinbkdev.vercel.app/tools/evm-rlp): Encode and decode Recursive Length Prefix data and inspect its nested structure.
- [BIP-39 Mnemonic to Ethereum Address (HD Wallet)](https://kevinbkdev.vercel.app/tools/evm-hd-wallet): Derive addresses from a BIP-39 mnemonic along BIP-44 paths, entirely offline.
- [Ethereum Vanity Address Generator (Prefix/Suffix)](https://kevinbkdev.vercel.app/tools/evm-vanity-address): Search for an Ethereum address with a custom prefix or suffix using background workers.

## Design & CSS

- [Color Contrast Checker - WCAG AA/AAA Ratio](https://kevinbkdev.vercel.app/tools/color-contrast-checker): Check WCAG 2 contrast ratios for text and UI colors with AA/AAA pass/fail results.
- [Tailwind Color Palette Generator (50-950)](https://kevinbkdev.vercel.app/tools/color-palette-generator): Generate Tailwind-style 50–950 shade scales from a base color and export them as CSS or config.
- [CSS Gradient Generator - Linear, Radial, Conic](https://kevinbkdev.vercel.app/tools/css-gradient-generator): Build linear, radial and conic CSS gradients visually with draggable color stops.
- [CSS Box Shadow Generator - Layered Shadows](https://kevinbkdev.vercel.app/tools/box-shadow-generator): Design layered CSS box shadows with live preview and copy-ready CSS and Tailwind output.
- [CSS clamp() Calculator - Fluid Typography](https://kevinbkdev.vercel.app/tools/css-clamp-calculator): Calculate fluid clamp() values for font sizes and spacing between two viewport widths.

## File & Media

- [Online Webcam Recorder & Camera Photo Capture](https://kevinbkdev.vercel.app/tools/camera-recorder): Take a picture or record a video from your webcam or camera.
- [PDF Digital Signature Checker (Offline)](https://kevinbkdev.vercel.app/tools/pdf-signature-checker): Inspect digital signatures, ByteRange integrity, certificates, and signer metadata inside PDF documents locally.
- [QR Code Reader from Image (No Upload)](https://kevinbkdev.vercel.app/tools/qr-code-reader): Decode QR codes from local image files and inspect payload contents without network uploads or camera requests.
- [Image Compressor & Converter: PNG, JPEG, WebP](https://kevinbkdev.vercel.app/tools/image-converter): Resize, compress and convert images between PNG, JPEG and WebP locally in your browser.

## System & Productivity

- [Chmod Calculator: Octal & Symbolic Permissions](https://kevinbkdev.vercel.app/tools/chmod-calculator): Convert three-digit Unix permissions between octal, symbolic, and decimal forms.
- [Emoji Picker: Copy Emoji, Shortcodes & Unicode](https://kevinbkdev.vercel.app/tools/emoji-picker): Searchable Unicode emoji directory with category filtering, shortcodes, and one-click copy to clipboard.

## Optional

- [Project principles](https://kevinbkdev.vercel.app/tools/about): how the tools are built (local-first, focused, accessible)
- [Glossary](https://kevinbkdev.vercel.app/tools/terms): formats and concepts, linked to the tools that use them