Your JWT. Your schema. Your .env. It never leaves this tab.
Every tool runs entirely in your browser — no server, no uploads, no logs.
Every tool you google — jwt.io, regex101, random JSON formatters — sends your input to somebody's server. That's your JWT, your API keys, your .env, your production schema sitting in a request log you don't control. DevTab doesn't do that.
Zero network requests
Client-side tools run in pure TypeScript. Open DevTools → Network while using any tool — nothing fires.
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Free tools need no signup. There is nothing to log because there is no server call.
AI tools are the exception
Only marked ✨ AI tools call our servers, and only when you click the button. Everything else stays local.
Quick access to our daily most-used client-side developer utilities.
110 tools across 12 categories
Text + JSON Diff
Line diff and structural JSON diff (key order ignored), with collapsed unchanged sections.
Regex Tester
Live match highlighting with all groups and indices, a common-pattern library, and AI explain.
String Escape / Unescape
Escape and unescape special characters for HTML Entities, JSON strings, and SQL values client-side.
Case Converter
Convert string case between camelCase, snake_case, kebab-case, PascalCase, and other popular styles.
Line Tools
Sort, deduplicate, reverse, trim, and filter lists of text lines client-side.
Lorem Ipsum Generator
Generate standard paragraphs/words and developer mock data (JSON, SQL, HTML) client-side.
Markdown Preview
Render markdown syntax and preview raw HTML output side-by-side client-side.
Reading Time Estimator
Calculate character, word, sentence, and paragraph counts alongside speaking and reading time metrics.
JWT Decoder
Decode JWT header and payload, and see the expiry countdown. Zero network requests, ever.
Base32 / Base58 / Base85
Encode and decode inputs across Base32, Base58 (Bitcoin), and Base85 (Z85) formats.
Hash Generator
Calculate MD5, SHA-1, SHA-256, and SHA-512 hashes for text or files locally.
HMAC Generator
Generate hash-based message authentication codes (HMAC) using standard SHA algorithms client-side.
AES Encrypt / Decrypt
Encrypt and decrypt text messages using standard AES-GCM-256 and PBKDF2 key derivation.
bcrypt Verifier
Validate bcrypt hash structures, cost factors, salts, and versions client-side.
TOTP / 2FA Code Generator
Generate RFC 6238 TOTP (Google Authenticator) 2FA verification codes client-side.
QR Code Generator
Generate scannable QR codes client-side, supporting custom foreground/background colors.
Password Breach Checker
Audit password strength against leak datasets securely using k-anonymity checks.
Passphrase Generator
Generate cryptographically secure Diceware passphrases with custom separators client-side.
PEM / Certificate Decoder
Decode X.509 certificates to extract Issuer, Subject, Expiry, and Serial Number details.
RSA Key Pair Generator
Generate RSA key pairs with custom sizes and signature hash algorithms client-side.
SSH Key Generator
Generate and format Ed25519/RSA SSH key pairs client-side using WebCrypto.
ROT13 / Caesar Cipher
Process character rotation shifts for Caesar and ROT13 ciphers.
QR Code Reader
Decode QR code images client-side using the browser-native BarcodeDetector API.
CSV ↔ JSON Converter
Convert CSV to JSON and JSON to CSV bidirectionally with support for nested object flattening.
YAML ↔ JSON
Convert YAML configurations to JSON structures and JSON keys back to YAML client-side.
UUID / ULID Generator
Bulk-generate UUID v1, UUID v4, and ULID identifiers with custom formatting options.
JSON ↔ XML
Convert JSON structure data payloads to XML formats and XML back to JSON client-side.
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal.
Unit Converter
Convert units of length, data size, temperature, speed, and weight instantly.
JSON → Types
Paste JSON, get a TypeScript interface, Pydantic model, Go struct, or Zod schema.
Slug Generator
Generate clean URL slugs from text strings, supporting word filtering and custom delimiters.
Strip HTML Tags
Strip HTML tags from text payloads, yielding clean markup-free string content.
Fake Data Generator
Generate realistic mock data records in JSON or CSV formats using a custom schema.
JSON Path Tester
Evaluate JSONPath query selectors to locate and match nodes in JSON documents client-side.
HEX Dump Viewer
Format paste strings or file bytes as hexadecimal grids with side-by-side ASCII maps client-side.
YAML ↔ TOML
Convert YAML parameter files to TOML formatting and TOML lines back to YAML client-side.
JSON Flattener / Unflattener
Flatten nested JSON object fields or unflatten dot-separated structures back to nested maps client-side.
JSON Array Tools
Sort, group, filter, and deduplicate JSON array structures client-side.
JSON Merger
Deep merge two JSON objects recursively with custom conflict resolution rules client-side.
Markdown Table Generator
Convert JSON array maps or CSV lines to formatted Markdown table syntax client-side.
Table → CSV / JSON
Convert pasted spreadsheet rows or HTML table structures to CSV or JSON arrays client-side.
JSON Formatter
Format, minify, and validate JSON in real time with line-level error highlighting.
SQL Formatter
Format SQL with keyword uppercasing and consistent, readable newlines.
XML Formatter
Format and validate XML using the browser's native DOMParser — no server round trip.
HTML Formatter
Prettify or minify HTML markup.
GraphQL Query Formatter
Beautify and indent raw inline GraphQL query structures.
JSON Schema Generator
Generate a drafts-compliant JSON Schema from a JSON sample, offline in your browser.
JSON Stringify & Parse
Stringify, parse, and minify JSON with configurable indent, key sorting, and Unicode escaping client-side.
CSV Formatter / Validator
Parse and format CSV text cells, validating column counts and alignment client-side.
CSS Formatter
Format or minify CSS and see the byte savings.
Color Converter
Convert between HEX, RGB, and HSL in any direction, with a live swatch preview.
WCAG Contrast Checker
Check relative luminance and contrast ratio of text and background colors for WCAG compliance.
CSS to Tailwind Converter
Map standard CSS declarations to utility Tailwind CSS class lists client-side.
CSS Gradient Builder
Generate linear and radial CSS gradient rules with multiple color stops and real-time previews.
Box Shadow Generator
Generate CSS box shadow rules with offset, blur, spread, color, and opacity sliders.
CSS Clip-Path Generator
Design CSS clipping shapes using standard presets and drag-and-drop coordinates editor.
Flexbox Visualizer
Configure and visualize flexbox alignments with growth, shrink, and wrap selectors.
CSS Grid Visualizer
Build and visualize grid layouts with columns count, gaps, and custom col/row spans.
CSS Specificity Calculator
Calculate and analyze the specificity score of CSS selectors according to W3C standards.
HTML Color Names
Browse and search W3C named CSS colors, hex codes, and categories.
Color Blend Mode Calculator
Preview all 12 CSS/Photoshop blend modes between two colors with adjustable opacity client-side.
SVG Optimizer
Optimize and compress SVG vector markup by stripping editor namespaces and comments.
Favicon Pack Generator
Generate standard web and mobile favicon assets from master images.
Font Pairing Previewer
Select and audit Google Fonts pairing combinations with dynamic styling imports.
Cubic Bezier Builder
Design custom spline timing curves with drag handles and transition comparison.
CSS Animation Generator
Configure keyframe animations with custom speeds, delays, and iterations.
Media Query Builder
Generate clean responsive CSS wrappers matching custom screen resolutions.
z-index Visualizer
Audit layering order on an isometric 3D stacking visualizer panel.
URL Inspector
Break a URL into every component — protocol, host, path, and query params, individually.
IP Subnet Calculator
Calculate subnet mask, network address, broadcast address, and host range from any CIDR notation client-side.
curl → Code
Paste a curl command, get Python, JavaScript, Go, Rust, or PHP with error handling included.
CORS Simulator
Simulate and verify preflight requests against CORS policy headers.
curl Command Builder
Compile requests and custom headers into standard cURL command scripts.
CSP Builder
Configure Content-Security-Policy directives and compile headers.
HTTP Header Analyzer
Analyze response header parameters and audit security header compliance.
DNS Lookup via DoH
Query DNS records directly from browser-native DNS-over-HTTPS (DoH) API endpoints.
OAuth 2.0 Flow Debugger
Simulate and audit OAuth 2.0 authorization grants and token exchanges.
Webhook Payload Inspector
Inspect payload structures and validate event metadata formats for common APIs.
robots.txt Validator
Parse and test crawl rules against request paths and User-Agent parameters.
Open Graph Previewer
Configure page metadata and preview social share cards for X, LinkedIn, and Slack.
API Response Size Calculator
Calculate payload bytes weight and evaluate structural optimizations.
Chmod Calculator
Toggle permission checkboxes to get octal and symbolic notation, with common presets.
Cron Builder
Build cron expressions from a 5-field UI or parse one back, with plain-English description and next run times.
.gitignore Generator
Build matching .gitignore settings for projects using language templates.
.env Diff
Compare .env.example vs .env — see missing keys, extra keys, and matches. Values masked by default.
Crontab History Viewer
Evaluate future execution run dates for standard cron syntax patterns client-side.
Timestamp Converter
Convert Unix timestamps (seconds/ms) to ISO, UTC, local, and relative time — and back.
Timezone Converter
Convert date and time between different timezones and calculate offsets.
Date Calculator
Calculate dates by adding or subtracting years, months, weeks, and days client-side.
Business Days Calculator
Count working business days between two dates, excluding weekends and custom holidays client-side.
Age Calculator
Calculate your exact age in years, months, and days alongside birthday countdowns client-side.
Meeting Time Planner
Coordinate overlapping working hours across multiple global timezones client-side.
DST Transition Checker
Audit daylight saving time transition offsets and dates for named timezones client-side.
ISO Week Calculator
Determine the standard ISO-8601 week number and year for any selected date client-side.
Time Duration Formatter
Convert time intervals bidirectionally between raw seconds and human duration strings client-side.
Leap Year Checker
Verify if a year is a leap year and check upcoming leap milestones client-side.
Unix Epoch Milestones
Display current UNIX epoch timestamps and remaining countdowns to major integer milestones client-side.
Bitwise Calculator
Compute AND, OR, XOR, NOT, and shift operations on 32-bit integers with binary/hex visualization.
Scientific Notation Converter
Convert numbers between standard decimal, scientific notation (e23), and engineering notation offline.
Roman Numeral Converter
Convert between Arabic integers (1–3999) and Roman numerals bidirectionally in the browser.
HTTP Status Codes
Searchable, color-coded reference of every HTTP status code and what it means.
Title & Description Length Checker
Check character counts and pixel widths of page titles and meta descriptions with live Google SERP simulation.
Schema.org JSON-LD Validator
Validate, parse, and check your Schema.org structured metadata in JSON-LD format.
sitemap.xml Validator
Validate and parse sitemap.xml files client-side, checking schemas, URL counts, limits, and parameters.
Open Graph Meta Checker
Extract, validate, and check Open Graph and Twitter Card metadata from HTML with live feed simulators.
Can I Use Check
Browse compatibility metrics for modern CSS and HTML5 layout features.
API Mock Server
Spin up mock REST endpoints instantly in-browser.
Network & APIHTTP Request Builder
Craft and replay HTTP requests with full control.
Network & APIOpenAPI / Swagger Viewer
Visualise and explore OpenAPI specs interactively.
Network & APIWebSocket Tester
Open WS connections and inspect frames live.
Network & APIDocker Compose Validator
Lint and validate docker-compose YAML client-side.
DevOpsKubernetes YAML Linter
Spot K8s manifest issues before applying.
DevOpsTerraform Formatter
Format HCL / Terraform files in the browser.
DevOpsGit Conflict Resolver
Visual 3-way merge for conflict markers.
Text & DiffMarkdown Slides
Turn Markdown into a simple slide deck.
Text & DiffSQL Schema Visualizer
Draw ER diagrams from CREATE TABLE statements.
FormattersProtobuf / gRPC Decoder
Decode binary protobuf payloads in the browser.
FormattersOTP / HOTP Verifier
Verify time-based and counter-based OTPs.
Security & EncodingSteganography Tool
Hide and reveal text inside PNG images.
Security & EncodingNumber Base Converter
Convert between any bases 2–36 with full breakdown.
Number & MathMatrix Calculator
Multiply, transpose, and find determinants.
Number & MathCode Complexity Scorer
Estimate cyclomatic complexity of any JS/TS snippet.
Fun & ViralAI Code Reviewer
Get AI-powered inline feedback on any code snippet.
AI ToolsAI Regex Builder
Describe what you want — get a working regex.
AI ToolsSimple. No surprises.
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