Tools That Work Offline

Count exact LLM tokens for GPT, Claude and Gemini prompts.

See if your system, context and user messages fit the model window.

Estimate GPT, Claude and Gemini API spend per call and per month.

Audit prompts for vague wording, missing formats and leaked secrets.

Validate JSONL and fine-tuning datasets line by line.

Pretty-print, minify, sort and deduplicate JSON Lines files.

Convert JSON Lines to a JSON array and back again.

Split documents into token-sized overlapping chunks for embedding.

Check that a model's JSON reply matches your JSON Schema.

Build function-calling schemas for OpenAI, Claude, Gemini, MCP and the AI SDK.

Validate Model Context Protocol tool definitions before you ship them.

Strip emails, keys, tokens and personal data before prompting an LLM.

Convert function-calling schemas between OpenAI, Anthropic, Gemini and MCP.

Wrap any JSON Schema into a ready-to-use function-calling tool.

Compare two prompt versions word by word with a token delta.

Compare two model responses to measure drift between runs or models.

Fit as many RAG chunks as possible into a model context budget.

Remove exact and near-duplicate rows from fine-tuning datasets.

Profile a JSONL training set: token stats, roles, duplicates and cost.

Convert between OpenAI chat, ShareGPT, Alpaca and prompt/completion.

Cosine, dot product and distance between two embedding vectors.

Inspect dimensions, norm, mean and spread of an embedding vector.

Generate an MCP, OpenAI or Anthropic tool schema from example arguments.

Lint an OpenAPI or Swagger spec for contract quality issues.

Diff two OpenAPI specs and flag breaking changes.

Audit an API for naming, casing and response consistency.

Turn a JSON API response into OpenAPI, JSON Schema or TypeScript.

Generate a Markdown changelog from two OpenAPI versions.

Pretty-print and beautify JSON with custom indentation.

Validate JSON syntax and see detailed error diagnostics.

Compress JSON by removing whitespace and show bytes saved.

Diff two JSON documents and list added, removed, and changed paths.

Explore JSON as a collapsible, color-coded tree.

Convert JSON into well-formed, indented XML.

Convert JSON documents to clean, readable YAML.

Flatten a JSON array of objects into a CSV spreadsheet.

Escape special characters for use inside a JSON string.

Reverse JSON string escaping back to readable text.

Explore JSON paths and evaluate simple JSONPath queries.

Infer a JSON Schema from a sample JSON document.

Auto-fix broken JSON: quotes, trailing commas, comments, and more.

Sort JSON object keys alphabetically, naturally, or by array field.

Merge two or more JSON documents with shallow/deep strategies.

Validate OpenAPI 3.x / Swagger 2.0 documents in JSON or YAML.

Validate JSON data against a JSON Schema (Draft-07) in your browser.

Count words, characters, sentences, and reading time.

Count characters and bytes with limit presets.

Convert text between 11 different letter cases.

Turn any text into a clean, URL-friendly slug.

Deduplicate lines of text with flexible matching.

Sort lines alphabetically, numerically, or by length.

Reverse text by character, word, line, or sentence.

Search and replace text with plain or regex matching.

Generate placeholder text for mockups and designs.

Compare two texts line-by-line with an LCS diff.

Analyze readability with Flesch score and syllable stats.

Add or remove line numbers from text with custom formatting.

Repeat text a set number of times with custom separators.

Trim, collapse, and clean up whitespace in text.

Shuffle a list of lines and optionally pick a random subset.

Split delimited text into aligned columns and re-join it.

Turn text into a big ASCII banner using letters and numbers.

Prettify and align Markdown tables with column alignment.

Detect non-ASCII, invisible, smart-quote, and emoji characters.

Generate acronyms, initials, or camelCase from phrases.

Obfuscate text with ROT13, zero-width spaces, or leetspeak.

Align delimited text into padded, readable columns.

Generate lorem ipsum text wrapped in HTML tags.

Generate random strings from a custom pattern.

Count how often each word appears in your text.

Normalize unicode, smart quotes, dashes, and whitespace.

Strip all emoji characters from text instantly.

Hard wrap text to a fixed column width.

Check and fix title case capitalization word by word.

Write Markdown with a live rendered preview and toolbar.

Inspect code points, categories, and byte lengths of every character.

Clean up filenames for safe cross-OS use.

Turn text into a natural voice — play it aloud or download the audio.

Dictate with your microphone and get a live, editable transcript.

A distraction-free notepad with multiple notes that auto-save in your browser.

Turn any text into a downloadable word cloud image.

Pull emails, links, domains and phone numbers out of any text.

Turn newline-separated lines into a quoted, comma-joined string.

Add text to the start or end of every line at once.

Compare two lists and see common, A-only and B-only items.

Remove line breaks and tabs, or swap them for any separator.

Split long text into chunks by characters, words, lines or a separator.

Beautify and indent messy HTML markup.

Beautify or minify CSS with safe string handling.

Design linear, radial, and conic gradients visually.

Layer multiple box-shadows with a live preview.

Visually build flexbox layouts and copy the CSS.

Design CSS grid layouts with live preview.

Fine-tune per-corner border radii visually.

Create frosted-glass UI effects with live preview.

Generate parametric SVG wave shapes for sections.

Generate a complete SEO and social meta tag block.

Build keyframe animations visually with a live preview.

Layer multiple text-shadows with a live preview.

Generate arrow and triangle shapes with borders or clip-path.

Design polygon clip-path shapes with a live preview.

Translate common Tailwind utility classes into plain CSS.

Build an editable HTML table and export HTML + CSS.

Convert between px, rem, em, %, pt, vw, and vh.

Searchable reference of common HTML character entities.

Tune blur, brightness, contrast, and more with a live preview.

Design custom scrollbars with live preview.

Simplify ratios and compute matching dimensions.

Build a custom property theme with a live preview.

Combine translate, rotate, scale, and skew with a live preview.

Create soft UI neumorphic shadows with a live preview.

Design named grid-template-areas visually.

Build responsive @media rules with breakpoint presets.

Compare and rank the specificity of CSS selectors.

Preview heading and body font combinations live.

Edit HTML, CSS, and JS in tabs with an instant sandboxed live preview.

Generate fluid typography clamp() CSS from min/max viewport and size.

Design a professional HTML email signature and copy it into any mail client.

One image in, a ready-to-copy icon pack out for iOS, Android, web, macOS, Windows and extensions.

Shrink JPEG, PNG, and WebP images without a server.

Resize images to exact pixel dimensions with locked aspect ratio.

Convert images between PNG, JPEG, and WebP in your browser.

Crop images by dragging a selection box, right in your browser.

Generate downloadable QR codes for any text or URL.

Strip comments, metadata, and whitespace from SVG markup.

Convert images to Base64 data URLs and back again.

Sample any pixel color from an uploaded image.

Inspect an image's dimensions, size, type, and aspect ratio.

Convert any image into ASCII text art in your browser.

Add a custom text watermark to your images.

Extract the dominant colors from any image.

Slice a sprite sheet into individual frame images.

Rotate images in 90° steps and flip horizontally or vertically.

Preview per-corner border-radius on your own image.

Convert SVG files to PNG images at any scale.

Generate solid or checkerboard placeholder images.

Generate a low-fidelity blurred placeholder preview.

Inspect EXIF, camera and GPS metadata in photos, then strip it out.

Generate scannable Code 128 and EAN-13 barcodes.

Add classic top and bottom captions to any image and download the meme as PNG.

Resize and convert many images at once in your browser.

Combine photos into a grid collage and download a PNG.

Crop a photo to official passport, visa and ID sizes at print DPI.

Erase the background from a photo and export a transparent PNG.

Draw or type a signature and export a transparent PNG.

Trace PNG or JPG images into clean, scalable SVG paths.

Convert iPhone HEIC/HEIF photos to JPG or PNG in your browser.

Combine images into one sprite sheet plus ready-to-paste CSS.

Add film grain or digital noise to an image with live preview.

Convert images to and from AVIF with quality control.

Convert WebP images to JPG or PNG, or encode images as WebP.

Turn any image into a full favicon pack with .ico, PNGs, manifest and HTML.

Preview how your page appears in Google search results.

Generate Open Graph and Twitter Card meta tags.

Build JSON-LD structured data for common schema types.

Create a robots.txt file with custom crawl rules.

Generate an XML sitemap from a list of URLs.

Generate canonical link tags to avoid duplicate content issues.

Analyze keyword frequency and density in your text.

Build JSON-LD FAQPage structured data from Q&A pairs.

Generate JSON-LD BreadcrumbList structured data.

Analyze HTML for missing or problematic meta tags.

Convert between CSV and JSON with delimiter and header options.

Convert YAML to JSON and JSON to YAML.

Convert XML to JSON and JSON to XML using the browser's DOMParser.

Convert Markdown to HTML with a live preview.

Convert numbers between binary, octal, decimal, hex, and custom bases.

Convert length, weight, temperature, area, volume, speed, and data-size units.

Convert CSV into a Markdown or HTML table with alignment options.

Parse simple SQL INSERT INTO statements into JSON rows.

Convert text to binary or octal codes and back.

Convert between numbers and Roman numerals.

Infer TypeScript interfaces or type aliases from JSON data.

Generate SQL INSERT statements from a JSON array of objects.

Convert CSV data into well-formed XML with custom tag names.

Convert TOML configuration files to JSON and back.

Convert between milliseconds, seconds, minutes, hours, days, and weeks.

Convert bytes, KB/MB/GB/TB with binary (KiB/MiB) or decimal units.

Convert between base64/data URI text and image previews.

Spell numbers out in words or format them as currency, ordinals and locale text.

Generate Go structs with JSON tags from JSON data.

Generate Python dataclasses from JSON data.

Convert HTML markup into clean Markdown syntax.

Generate SQL INSERT statements from CSV data.

Convert between spreadsheet column numbers and letters.

Convert INI config files to JSON and back.

Convert nested JSON config into .env variables.

Convert Markdown content into a JSX React component.

Beautify and normalize YAML with a hand-written parser.

Beautify XML and validate well-formedness using DOMParser.

Generate a Zod validation schema and TypeScript type from JSON.

Translate text to Morse code and back, with audio playback.

Spell out text using the NATO phonetic alphabet.

Open a CSV as a sortable, searchable table and edit cells before exporting.

Generate Kotlin data classes from any JSON payload.

Turn JSON into Java records or POJOs with getters and setters.

Turn JSON into Swift structs that conform to Codable.

Convert Apple property lists to JSON and back.

Convert Localizable.strings files to JSON and back.

Convert Android string resources to JSON and back.

Generate Dart model classes with fromJson and toJson from JSON.

Turn JSON into serde-ready Rust structs.

Encode or decode text to/from Base64, UTF-8 safe.

Encode or decode strings using encodeURIComponent/encodeURI.

Encode or decode HTML entities in text.

Generate MD5, SHA-1/256/384/512 hashes of text.

Sign a message with HMAC using a secret key.

Decode a JWT's header and payload, and check expiry.

Encrypt or decrypt text with AES-GCM and a passphrase.

Generate cryptographically secure random strings.

Encode or decode text with ROT13 or any Caesar shift.

Hash text or a file and compare against an expected checksum.

Generate RSA or ECDSA key pairs and export them as PEM.

Compute SHA-1/256/384/512 digests of a local file.

Encode or decode text with the classic Vigenère cipher.

Encode or decode text using RFC 4648 Base32.

Generate and verify bcrypt password hashes with adjustable cost.

Build and sign a JWT with HS256/384/512 from a header, payload, and secret.

Generate a Subresource Integrity hash for scripts and stylesheets.

Build or decode an HTTP Basic Authorization header.

Convert certificates and keys between PEM and DER encoding.

Convert any file to a Base64 data URI, or decode Base64 back to a file.

Convert JSON Web Keys to PEM and PEM keys back to JWK.

Generate bulk RFC 4122 v4 UUIDs with formatting options.

Generate sortable ULIDs with timestamp and random components.

Create secure passwords with custom length and character sets.

Generate arrays of mock JSON records from a simple field schema.

Generate random fake user records with names, emails, and addresses.

Build a .gitignore file from built-in language and OS presets.

Generate random integers, decimals, dice rolls, and shuffled lists.

Generate Luhn-valid fake card numbers for testing.

Pick random emoji or symbols from curated categories.

Spin a wheel to pick a random name or option fairly.

Build a downloadable .ics calendar invite with reminders and recurrence.

Build the AASA file that powers iOS universal links.

Build Apple's PrivacyInfo.xcprivacy file for App Store submission.

Convert between Unix timestamps and human-readable dates.

Format a date using custom patterns and Intl presets.

Convert a datetime across multiple IANA timezones at once.

Calculate the difference between two dates, or add/subtract time.

Calculate exact age and countdown to the next birthday.

Explain a 5-field cron expression and list upcoming run times.

Convert dates and durations to and from ISO 8601 format.

Find the ISO week number, day of year, and quarter for any date.

Count business days between two dates, excluding holidays.

Live countdown to any date and time.

Check if a year is a leap year and find nearby leap years.

Total up work hours across shifts with breaks and hourly pay.

Convert a date to its day-of-year number, or back again.

Convert a list of Unix timestamps to readable dates in bulk.

Precision stopwatch with laps plus a countdown timer with alarm.

Focus timer with customisable work sprints and breaks.

Convert colors between HEX, RGB, HSL, HWB, OKLCH and CMYK.

Check WCAG 2.1 contrast ratio between two colors.

Generate complementary, analogous, triadic and other palettes.

Generate a 50–950 tint and shade scale from one color.

Simulate how a palette looks with common color vision deficiencies.

Blend two colors with a ratio slider and preview CSS blend modes.

Extract and normalize colors from CSS gradients or lists.

Generate random colors and palettes with HSL constraints.

Turn a hex color into SwiftUI, UIKit and asset catalog code.

Calculate network, broadcast, host range, and mask from an IPv4 CIDR.

Expand a CIDR block into individual addresses, or compress a range into CIDR blocks.

Convert IPv4 to decimal/hex/binary, and expand or compress IPv6.

Break a URL into protocol, host, port, path, query, and hash.

Convert between URL query strings and JSON, with nested bracket support.

Parse a user-agent string into browser, engine, OS, and device type.

Searchable reference of HTTP status codes with meaning and usage guidance.

Validate and reformat MAC addresses, and look up the OUI vendor prefix.

Search well-known TCP/UDP ports and their services.

Look up common HTTP headers and explain pasted raw headers.

Searchable reference of DNS record types with examples.

Expand an IPv6 address to full form or compress it to shorthand.

Search file extensions and their MIME types.

Plan Cache-Control, ETag and max-age headers for any asset type.

Decode WebSocket frame bytes into opcode, flags, mask and payload.

Validate and normalise lists of IPv4, IPv6 and CIDR entries offline.

Build OAuth 2.0 / OIDC authorization URLs with PKCE support.

Parse Set-Cookie headers and flag security issues.

Diff two sets of HTTP headers, case-insensitively.

Query A, AAAA, MX, TXT, NS, CNAME and other DNS records for any domain.

Analyse a HAR export: slow requests, errors, sizes and host breakdowns.

Convert internationalised domain names to punycode and back.

Calculate X% of Y, percent change, and reverse percentages.

Compute mean, median, mode, variance, and more from a list of numbers.

Solve, simplify, and scale ratios and aspect ratios.

Add, subtract, multiply, divide, and simplify fractions.

Check primality, factorize numbers, list primes, and compute GCD/LCM.

Convert between decimal, scientific, and engineering notation.

Add, multiply, transpose, and invert matrices with an editable grid.

Round, floor, ceil, or truncate a list of numbers to decimals or multiples.

Solve ax² + bx + c = 0 with real or complex roots.

Find the greatest common divisor and least common multiple of numbers.

Project investment growth with compounding and recurring contributions.

Compute logarithms of any base and exponentiation results.

Generate arithmetic, geometric, or Fibonacci-like number sequences.

Calculate monthly loan payments, total interest, and view the full amortization schedule.

Calculate your Body Mass Index and healthy weight range.

Calculate tip amount and split the bill evenly among a group.

Calculate a discounted price plus sales tax and total savings.

Test regular expressions with live match highlighting.

Build cron expressions visually with a human-readable description.

Convert .env files to JSON, YAML, or shell exports.

Escape and unescape strings for JSON, JS, HTML, XML, SQL, RegExp, and shell.

Convert identifiers between camelCase, snake_case, kebab-case, and more.

Minify or beautify JavaScript, CSS, HTML, JSON, XML and SQL.

Unzip ZIP, TAR, GZ, 7Z, RAR and more in your browser — browse folders, preview and download files.

Open an APK, decode its manifest and browse or download every file inside.

Send live API requests and generate curl, fetch, axios snippets.

Validate and inspect UUIDs, including version and timestamp.

Convert a curl command into JavaScript fetch() code.

Convert a JS object literal into strict, valid JSON.

Searchable reference of common git commands with copy buttons.

Lint a Dockerfile for common best-practice issues.

Validate package.json fields, semver ranges, and scripts.

Compare versions and test semver ranges (^, ~, >=).

Side-by-side line diff of two code snippets with stats.

Sort, dedupe, and filter lines with regex include/exclude.

Searchable regex syntax reference with examples and copy buttons.

Unix permission calculator: checkboxes, octal, and symbolic.

Format and indent SQL queries for readability.

Validate YAML and preview it as JSON.

Generate Apache .htaccess redirect and rewrite rules.

Format and indent GraphQL queries and mutations.

Remove comments from JS, HTML, Python, or SQL source.

Convert indentation between tabs and spaces.

Compare two JSON documents and see added, removed and changed keys.

Generate Nginx snippets for redirects, proxies, caching and security headers.

Build a linked table of contents from Markdown headings.

Create shell aliases for Bash, Zsh or Fish with correct quoting.

Translate whole crontab files into plain English, line by line.

Parse a curl command into method, URL, headers, and body.

Inspect a pasted webhook request and verify its HMAC signature.

Browse a GraphQL SDL schema's types, queries, and mutations.

Open a .sqlite/.db file in your browser and run SQL against it.

Write schema and seed SQL, then run queries against an in-memory database.

Convert install/run/exec commands between npm, yarn, pnpm and bun.

Build ~/.ssh/config Host entries from simple form fields.

Open a live WebSocket connection, send frames and read replies.

Record your screen, window or tab with optional microphone audio.

Measure your typing speed in WPM with live accuracy tracking.

Turn code snippets into shareable syntax-highlighted images.

Build ffmpeg commands for video and audio with explained flags.

Searchable ffmpeg command examples for video, audio and streaming.

Run real ffmpeg commands on your video, audio or image — no install.

Validate IBANs with the mod-97 checksum and country length rules.

Check card numbers with the Luhn algorithm and detect the brand.

Find expensive SQL patterns, missing filters and index opportunities.

Write and run JavaScript or TypeScript with a live console.

Validate Kubernetes manifests and catch risky container settings.

Check docker-compose.yml for errors, bad ports and risky settings.

Analyse nginx.conf for syntax, security and performance issues.

Validate a GitHub Actions workflow YAML and catch security and structure mistakes.

Points, pixels, scale factors and App Store screenshot sizes for iPhone, iPad and Apple Watch.

Convert dp, px and sp across every Android density bucket.

Searchable Android permission list with protection levels and manifest snippets.

Build a production-ready systemd .service unit file.

Create an .editorconfig file with per-language overrides.

Count code, comment and blank lines in any source file.

Generate C# classes or records from JSON, with nullable reference types.

Convert between PHP serialize() format and JSON.

Convert HTML markup into clean React/JSX component code.

Convert Maven POM XML to Gradle Kotlin DSL and back.

Convert Java .properties files to JSON and back, with nested keys.

Download an .m3u8 HLS stream and save it as a single MP4 file.

Cut a clip out of any video by dragging start and end handles.

Shrink large video files by lowering bitrate, resolution and frame rate.

Resize or crop video to 9:16, 1:1, 4:5 and other social presets.

Convert video between MP4 and WebM with resolution control.

Extract the soundtrack from a video and save it as WAV or Opus.

Turn any part of a video into a looping animated GIF.

Convert an animated GIF into a far smaller MP4 or WebM video.

Grab stills from a video, or build a contact sheet of thumbnails.

Play M3U8 (HLS), MP4, WebM and local video files right in the browser.

Inspect a PDF's title, author, version, page count and encryption.

Pull readable text out of uncompressed PDF content streams.

Render Markdown into a printable page and save it as a PDF.

Turn pasted HTML into a print-ready page you can save as PDF.

Combine JPG, PNG or WebP images into a single PDF, offline.

Merge several PDFs into one file or split pages out of a PDF.

Build a professional invoice with line items, tax and totals, then save it as a PDF.

Reorder, rotate, reverse and delete PDF pages, then save a new file.

Stamp text watermarks across every page of a PDF.

Convert PDF pages to PNG, JPEG or WebP images at any resolution.

Shrink a PDF's file size with screen, ebook or print presets.

Remove a known PDF password or add password protection to a PDF.

Estimate password entropy, crack time, and get actionable advice.

Build a Content-Security-Policy header from per-directive sources.

Grade HTTP response headers against security best practices.

Decode a JWT and audit its claims for common issues.

Generate .htpasswd lines using SHA-1 or plain text.

Scan pasted code or text for likely leaked secrets.

Generate CORS headers/config for Nginx, Apache, Express, or Workers.

Generate time-based one-time passcodes from a Base32 secret.

Scan robots.txt for accidental disclosure of sensitive paths.

Decode a PEM CSR or certificate into its ASN.1 structure.

Generate a valid RFC 9116 /.well-known/security.txt file.

Generate password policy rules, regex and copy for NIST or PCI presets.

Build a Permissions-Policy header controlling camera, geolocation and more.

Pick a Referrer-Policy value and get header/meta/server snippets.

Check if X-Frame-Options and CSP frame-ancestors block framing.

Parse an OpenSSH public key and show its SHA256/MD5 fingerprints.