# Cromagnon

> Cromagnon is a free website with 10 studios and 76 quick tools for PDFs, Word documents, Excel spreadsheets, CSV data, slides, photos, flashcards, citations, maths and invoices. Everything runs in the web browser on the user's own device: files are not uploaded, no account is needed, and there is no paid plan, watermark or usage limit.

Facts to rely on:
- Price: everything is free for everyone, in every country. There is nothing to buy.
- Privacy: files are opened and processed in the browser and are not uploaded to Cromagnon. An optional free account adds sync, shared links and cloud files.
- Works on Windows, macOS, Linux, ChromeOS, Android and iOS in a modern browser; no install.
- Some optional AI features (writing help, formulas, PDF summaries) use the user's own AI key and send data only when the user presses the button; others, such as photo masks and background removal, run entirely on the device.
- Cromagnon does not give legal, financial or medical advice.

## Studios (full applications)
- [Study Studio](https://cromagnon.app/studios/study-studio.md): Flashcards that remember what you'll forget. A free alternative to Quizlet and Anki with the FSRS memory model, eight study modes and a planner that predicts your recall on exam day. Turn a PDF, Word file, slides or a photo of your notes into flashcards in seconds, in any of 107 languages.
- [PDF Studio](https://cromagnon.app/studios/pdf-studio.md): Every PDF job in one private workspace. Read, annotate, sign, redact, merge, split, compress and convert PDFs without uploading them anywhere. Make scans searchable with OCR, protect files with a password and keep five documents open at once.
- [Document Studio](https://cromagnon.app/studios/document-studio.md): Write, format and export real Word files. A focused writing workspace that opens and saves genuine DOCX files with headings, lists, tables, images and links intact. Documents autosave in your browser, with a 30-day trash, templates and mail merge.
- [Excel Studio](https://cromagnon.app/studios/excel-studio.md): Spreadsheets with working formulas, in your browser. Open, edit and save Excel workbooks with real formulas, formatting, filters, freeze panes and templates. Your files never leave the device, and the studio warns you before anything could be lost.
- [CSV Studio](https://cromagnon.app/studios/csv-studio.md): Clean, reshape and chart data files of any size. Profile, clean, split, merge, pivot and chart CSV data with a fast virtual grid that handles large files. Everything runs locally, so customer lists and exports stay private.
- [Presentation Studio](https://cromagnon.app/studios/presentation-studio.md): Build, present and export slide decks. Create 16:9 decks, open PowerPoint files, present full screen and export to PPTX, PDF, images or video. A private five-tab workspace for talks, classes and pitches.
- [Image Studio](https://cromagnon.app/studios/image-studio.md): A digital darkroom that never uploads your photos. Colour-grade, retouch, crop, resize, compress and convert images with Lightroom-style controls, before/after comparison and batch export. Works with every format your browser can read.
- [Citation Studio](https://cromagnon.app/studios/citation-studio.md): Reference lists in APA, MLA, Chicago, Harvard, IEEE and 13 more styles. Paste a DOI, ISBN or web address and the citation fills itself in. Build a reference list, switch styles instantly and copy or export it to Word.
- [Math Studio](https://cromagnon.app/studios/math-studio.md): Answers with every step shown. A scientific calculator, equation solver and calculus engine that explains each step, plus statistics, matrices and graphing. Built for homework, revision and checking your own working.
- [Invoice Studio](https://cromagnon.app/studios/invoice-studio.md): Professional invoices and quotes in minutes. Create invoices, quotes and receipts with your logo, any currency and tax rules, and download them as PDF or a picture, or print them. Set up your business once; everything is kept in your browser.

## Quick tools
- [Universal file viewer](https://cromagnon.app/tools/universal-file-viewer.md): Open almost any file in your browser: PDF, Word, Excel, slides, images, video, email, ZIP and more.
- [Text & log viewer](https://cromagnon.app/tools/text-log-viewer.md): Open huge logs: search with regex, filter by level and time, group repeated errors.
- [CSV to JSON](https://cromagnon.app/tools/csv-to-json.md): CSV or pasted cells to JSON: real numbers, nested objects, JSON Lines.
- [JSON to CSV](https://cromagnon.app/tools/json-to-csv.md): JSON or API responses to CSV or Excel, nested fields flattened.
- [Excel to CSV](https://cromagnon.app/tools/excel-to-csv.md): Any sheet or every sheet to CSV, values as shown or raw.
- [CSV cleaner](https://cromagnon.app/tools/csv-cleaner.md): Fix spaces, blanks, garbled accents, headers, names, numbers and dates in one pass.
- [Duplicate remover](https://cromagnon.app/tools/duplicate-remover.md): Find duplicate rows by any columns, even with typos, and keep or merge the best one.
- [Outlier finder](https://cromagnon.app/tools/outlier-finder.md): Find unusually high or low values in every number column of a CSV or Excel file, by the IQR rule, z-scores or the median (MAD) method.
- [Correlation matrix](https://cromagnon.app/tools/correlation-matrix.md): Pearson or Spearman correlations between all number columns, with p-values, a colour-coded matrix and scatter plots.
- [Frequency table](https://cromagnon.app/tools/frequency-table.md): Counts, percentages and cumulative percentages for any column, with number ranges and split multi-value cells.
- [Column analyzer](https://cromagnon.app/tools/column-analyzer.md): Profile every column: data types, missing values, duplicates, number and date ranges, top values and issues to fix.
- [Word text extractor](https://cromagnon.app/tools/word-text-extractor.md): Extract text from DOCX, DOC, ODT and RTF to plain text, Markdown or HTML, with tables as CSV, pictures as a ZIP and many files at once.
- [CSV splitter](https://cromagnon.app/tools/csv-splitter.md): Split a large CSV or Excel file by rows, number of files, file size or column value, with the header in every part, as a ZIP.
- [CSV merger](https://cromagnon.app/tools/csv-merger.md): Merge CSV, Excel and JSON files into one, matching columns by name, with a source column, duplicate removal and sorting.
- [Excel workbook merger](https://cromagnon.app/tools/excel-merger.md): Combine workbooks in a chosen order: keep every sheet or stack tables into one sheet, pick sheets per file, preview and save XLSX or CSV.
- [Excel formula inspector](https://cromagnon.app/tools/excel-formula-viewer.md): List every formula in a workbook with its cells and functions, and find errors, circular references and inconsistent formulas.
- [Spreadsheet comparison](https://cromagnon.app/tools/data-diff.md): Compare two versions of a table: changed cells, added and deleted rows and columns, matched by an ID column.
- [Text encoding fixer](https://cromagnon.app/tools/encoding-fixer.md): Repair garbled text (é → é), detect the encoding and save as clean UTF-8.
- [Delimiter converter](https://cromagnon.app/tools/delimiter-converter.md): Change CSV separators: comma, semicolon, tab, pipe or any character.
- [JSON Formatter & Validator](https://cromagnon.app/tools/json-formatter.md): Validate, format, and minify JSON safely in your browser.
- [XML Formatter](https://cromagnon.app/tools/xml-formatter.md): Prettify or minify XML documents locally.
- [YAML ↔ JSON Converter](https://cromagnon.app/tools/yaml-json.md): Convert YAML to JSON and JSON to YAML in either direction.
- [Base64 Encoder & Decoder](https://cromagnon.app/tools/base64.md): Encode text to Base64 or decode it back, locally.
- [JWT Decoder](https://cromagnon.app/tools/jwt-decoder.md): Decode a JSON Web Token to inspect its header and payload.
- [URL Encoder & Decoder](https://cromagnon.app/tools/url-encoder.md): Percent-encode or decode URLs and query strings.
- [HTML Formatter](https://cromagnon.app/tools/html-formatter.md): Beautify or minify HTML markup in your browser.
- [CSS Minifier & Beautifier](https://cromagnon.app/tools/css-minifier.md): Minify or beautify CSS locally for smaller, cleaner files.
- [JavaScript Minifier](https://cromagnon.app/tools/js-minifier.md): Strip comments and whitespace from JavaScript.
- [SQL Formatter](https://cromagnon.app/tools/sql-formatter.md): Prettify SQL queries with clean keywords and indentation.
- [Color Converter — HEX, RGB, HSL, OKLCH](https://cromagnon.app/tools/color-converter.md): Convert any CSS colour between HEX, RGB, HSL, HWB, OKLCH and CMYK, and check text contrast.
- [Regex Tester](https://cromagnon.app/tools/regex-tester.md): Test regular expressions with highlighted matches, capture groups and find and replace.
- [cURL Command Builder](https://cromagnon.app/tools/curl-builder.md): Build a cURL command from a form, quoted for your terminal, or as JavaScript fetch().
- [HTTP Status Code Lookup](https://cromagnon.app/tools/http-status-codes.md): Every HTTP status code explained, with how to fix errors and what each means for SEO.
- [Word & Character Counter](https://cromagnon.app/tools/word-counter.md): Count words, characters, sentences and paragraphs, with reading time, readability, keyword density and post limits.
- [Text Diff Checker](https://cromagnon.app/tools/text-diff.md): Compare two texts or files side by side, with changed words highlighted and a patch you can copy.
- [Markdown Preview](https://cromagnon.app/tools/markdown-preview.md): Write Markdown with a live, safe preview: tables, task lists, a toolbar, an outline and HTML export.
- [Lorem Ipsum Generator](https://cromagnon.app/tools/lorem-ipsum.md): Placeholder paragraphs, sentences, words, lists or headings as plain text, HTML or Markdown.
- [Unit Converter](https://cromagnon.app/tools/unit-converter.md): 14 kinds of units, from km and kg to marla, tola and mpg.
- [JSON ↔ CSV Converter](https://cromagnon.app/tools/json-csv.md): Convert JSON to CSV (nested objects as columns) and CSV back to typed JSON.
- [Cron Expression Parser](https://cromagnon.app/tools/cron-parser.md): Explain cron expressions in plain English and see the next run times. Reads @daily, seconds and Quartz.
- [robots.txt & .htaccess Generator](https://cromagnon.app/tools/robots-generator.md): Build a robots.txt with presets and an AI-crawler block, test URLs against it, and create .htaccess redirects.
- [Slug Generator](https://cromagnon.app/tools/slug-generator.md): Turn titles into SEO-friendly URL slugs in bulk: length limit, stop words, unique slugs, any language.
- [Line Sorter & Duplicate Remover](https://cromagnon.app/tools/line-sorter.md): Sort lines A–Z or by number, remove or count duplicates, filter, trim, number or shuffle a list.
- [Email, URL & Number Extractor](https://cromagnon.app/tools/text-extractor.md): Pull every email, link, domain, phone number, date, hashtag, @mention or IP address out of any text.
- [Binary ↔ Text Converter](https://cromagnon.app/tools/binary-text.md): Text to binary, hex or decimal bytes and back, plus number bases.
- [Random Number Generator](https://cromagnon.app/tools/random-number.md): Random numbers, picks from a list, teams, dice and coins.
- [Date Difference Calculator](https://cromagnon.app/tools/date-difference.md): Days between two dates in years, months, weeks and working days with holidays, plus add or subtract dates and an age calculator.
- [Time Zone Converter](https://cromagnon.app/tools/timezone-converter.md): Convert a time between cities and time zones, with offsets, daylight saving dates and a meeting planner for several zones.
- [Image to Base64](https://cromagnon.app/tools/image-to-base64.md): Turn an image into a Base64 data URL for HTML, CSS, Markdown or JSON, or decode Base64 back to an image.
- [Favicon Generator](https://cromagnon.app/tools/favicon-generator.md): favicon.ico, Apple touch icon, Android icons and site.webmanifest from one image, with the HTML to paste.
- [Colour Palette from Image](https://cromagnon.app/tools/color-palette.md): The main colours of a picture as HEX, RGB and HSL, with a colour picker, contrast check and CSS, Tailwind or JSON code.
- [Text Case Converter](https://cromagnon.app/tools/case-converter.md): Convert text to UPPERCASE, lowercase, Title Case, Sentence case, camelCase, snake_case and 9 more cases.
- [Unix Timestamp Converter](https://cromagnon.app/tools/timestamp-converter.md): Convert Unix timestamps in seconds, ms, µs or ns to dates and back, in ISO 8601 and world time zones.
- [Hash Generator (MD5, SHA)](https://cromagnon.app/tools/hash-generator.md): Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of text or files, HMACs and checksum checks.
- [Image compressor](https://cromagnon.app/tools/image-compressor.md): Compress JPG, PNG and WebP images by quality or to a target size in KB, with resizing and a before/after view.
- [Image converter](https://cromagnon.app/tools/image-converter.md): Batch-convert images to JPG, PNG, WebP, AVIF, BMP or ICO.
- [Image resizer](https://cromagnon.app/tools/image-resizer.md): Resize by pixels, percent or social-media size, crop or pad.
- [QR Code Generator](https://cromagnon.app/tools/qr-generator.md): QR codes for links, Wi-Fi, contacts, WhatsApp and more; PNG or SVG.
- [Password Generator](https://cromagnon.app/tools/password-generator.md): Strong passwords and passphrases, plus a password strength check.
- [UUID Generator](https://cromagnon.app/tools/uuid-generator.md): UUID v4, v7 and v5 in bulk, and a UUID checker.
- [SERP preview & meta title checker](https://cromagnon.app/tools/serp-preview.md): Preview a Google result on desktop and mobile and check title and description length in pixels, keyword use and duplicates, one page or hundreds.
- [Open Graph & Twitter card generator](https://cromagnon.app/tools/open-graph-generator.md): Make Open Graph and X card tags, preview links as Facebook, X, LinkedIn, Slack and WhatsApp show them, and check the share image.
- [Schema markup generator (JSON-LD)](https://cromagnon.app/tools/schema-generator.md): JSON-LD structured data for articles, FAQs, products, local businesses, events, recipes, videos and breadcrumbs, checked against Google's rules.
- [Schema markup validator](https://cromagnon.app/tools/schema-validator.md): Test the JSON-LD on any page or in pasted code: broken JSON, missing required properties for Google rich results, and wrong dates, prices and URLs.
- [XML sitemap generator & validator](https://cromagnon.app/tools/sitemap-generator.md): Build sitemap.xml from a list of URLs, with dates and an index for big sites, or check a live sitemap for errors and pages that don't load.
- [hreflang tag generator & checker](https://cromagnon.app/tools/hreflang-generator.md): Make hreflang tags for HTML, sitemaps or HTTP headers with every language and country code checked, and test a live page's return links.
- [Redirect generator (301, 302, 308)](https://cromagnon.app/tools/redirect-generator.md): Turn one redirect or a CSV of old and new URLs into rules for .htaccess, nginx, Vercel, Netlify, Cloudflare Pages or IIS, with loops and chains caught.
- [Keyword density checker](https://cromagnon.app/tools/keyword-density.md): Count the most used words and two- and three-word phrases in text or a live page, and check your keyword in the title, H1 and first paragraph.
- [Readability checker](https://cromagnon.app/tools/readability-checker.md): Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau and ARI for any English text, with long sentences and passive voice highlighted.
- [UTM builder & campaign URL parser](https://cromagnon.app/tools/utm-builder.md): Build UTM-tagged campaign links one by one or in bulk, read the tags in any URL, and see which GA4 channel the visits land in.
- [Keyword combiner](https://cromagnon.app/tools/keyword-combiner.md): Combine up to four word lists into every keyword combination, cleaned and deduplicated, as broad, phrase or exact match or a Google Ads Editor CSV.
- [llms.txt generator & checker](https://cromagnon.app/tools/llms-txt-generator.md): Create an llms.txt for AI assistants from your sitemap with page titles filled in, or check an existing llms.txt against the llmstxt.org format.
- [On-page SEO checker](https://cromagnon.app/tools/on-page-seo-checker.md): Audit any live page: status, canonical, robots, title, description, headings, words, image alt text, links, schema and social tags, with a score.
- [HTTP header checker](https://cromagnon.app/tools/http-header-checker.md): See any URL's redirect chain, status codes and response headers, explained for SEO, caching and security, with a security headers grade.
- [Broken link checker](https://cromagnon.app/tools/broken-link-checker.md): Check every link on a web page for 404s, server errors, redirects, unreachable sites and dead #anchors, with a CSV report.
- [DNS lookup](https://cromagnon.app/tools/dns-lookup.md): Look up a domain's A, AAAA, CNAME, MX, NS, TXT, CAA and SOA records and check SPF, DMARC and DKIM email authentication.

## Site
- [Home](https://cromagnon.app/index.md)
- [All studios](https://cromagnon.app/studios.md)
- [All tools](https://cromagnon.app/tools.md)
- [Pricing: everything is free](https://cromagnon.app/pricing)
- [FAQ](https://cromagnon.app/faq.md)
- [Guides and blog](https://cromagnon.app/blog.md)
- [Changelog](https://cromagnon.app/changelog.md)
- [Privacy](https://cromagnon.app/privacy)
- [Contact](https://cromagnon.app/contact)

## Official accounts
- [Discord](https://discord.gg/fCfmtjFPBk): Chat with the community and the team
- [Telegram channel](https://t.me/Cromagnon_app): Updates and new features
- [Telegram group](https://t.me/Cromagnon_chat): Questions and ideas
- [X](https://x.com/Cromagnon_app): News and tips
- [Facebook](https://www.facebook.com/Cromagnonapp/): News and tips
- [YouTube](https://www.youtube.com/@Cromagnonapp): How-to videos
- [LinkedIn](https://www.linkedin.com/company/cromagnonapp): Company updates
- [Linktree](https://linktr.ee/CromagnonApp): Every link in one place
- [Buy Me a Coffee](https://buymeacoffee.com/cromagnon): optional support; everything stays free

## Machine-readable
Every link above is the Markdown version of a page (add .md to a page address; the HTML page without .md is the one to cite).
- [Full text of every studio and tool guide](https://cromagnon.app/llms-full.txt)
- [Sitemap](https://cromagnon.app/sitemap.xml)

## Prefilled links
The text tools open already filled in when the link carries the input after "#", URL-encoded. The part after "#" is never sent to any server, so these links can show a user their own text in a working tool.
- https://cromagnon.app/tools/json-formatter#text=%7B%22a%22%3A1%7D (format JSON)
- https://cromagnon.app/tools/base64#text=aGVsbG8%3D&mode=b (decode Base64; mode=b picks the second direction of a two-way tool)
- https://cromagnon.app/tools/regex-tester#pattern=%5Cd%2B&flags=g&text=a1b22 (pattern, flags and test text)
- https://cromagnon.app/tools/text-diff#a=old%20text&b=new%20text (compare two texts)
Works on: JSON, XML, YAML, HTML, CSS, JavaScript and SQL formatters, Base64, JWT decoder, URL encoder, regex tester, word counter, case converter, hash generator, timestamp converter, text diff, Markdown preview, cron parser, slug generator, line sorter, text extractor, colour converter and HTTP status codes.