Built For The Way You Work.
Discover everything Monstera has to offer, from everyday PDF tasks to advanced document workflows. With over 150 professional PDF tools, and an AI assistant, Monstera gives you the freedom to create, edit, convert, secure and manage documents, completely free and open source. Explore its features below.
Screenshots of Monstera with sample documents.
Thirteen groups of tools, all included, all free.
Enjoy fast, smooth viewing, whether you're working with a single-page form or a scanned archive containing thousands of pages. Navigate effortlessly and keep multiple documents open in tabs.
Organize and restructure your PDFs with ease, from rotating and rearranging individual pages to combining multiple documents into one, all within the same workspace.
Highlight, annotate, and mark up your PDFs just as you would on paper. Add notes, drawings, and comments, all neatly organized for easy review.
Edit existing text directly in your PDFs while preserving the original formatting wherever possible. Monstera intelligently matches fonts and uses the closest available alternative when needed.
Fill out existing PDF forms or create your own with interactive fields. Customize field properties, control navigation order, and make your forms easy for anyone to complete.
Turn scanned documents and handwritten content into searchable, selectable text with OCR support for 14 languages. Monstera detects scanned pages automatically and processes them locally, keeping your documents on your computer.
Protect sensitive documents with advanced security features, including permanent redaction, password protection, and digital signatures. Remove confidential information completely, including hidden data and metadata, and securely sign, certify, and verify your PDFs.
Compare different versions of a document to quickly identify changes and review revisions. View documents side by side, examine differences, and review comments before approving or sharing.
Create PDFs from blank pages, images, Markdown, CSV files, or Microsoft Office documents. Import files from Google Drive or OneDrive, with offline Office conversion powered by ONLYOFFICE running in an isolated sandbox for added security.
Convert PDFs to Word, Excel, PowerPoint, images, and other formats while preserving content and layout wherever possible. Optimize file sizes, create archival-quality PDFs, and choose the export settings that best suit your needs.
Work smarter with an AI assistant built directly into Monstera. Ask questions, summarize and analyze documents, extract information, translate content, and draft text. Get answers with clickable page references, extend your research with web search, and choose from ten AI providers using your own API key.
Get the guidance you need without interrupting your workflow. Press F1 anywhere in Monstera to open the relevant help article, with clear, step-by-step instructions and direct links to tools. All 143 help articles are available offline, so assistance is always within reach. The same articles are in the online Help.
Monstera is designed to WCAG 2.1 AA and checked by automated accessibility tests on every change. Enjoy full keyboard navigation, accessible display options, and tools that make working with PDFs easier for everyone. Learn more in our accessibility statement.
Turn your documents into an interactive source of information with Monstera's built-in AI assistant. Ask questions, summarize lengthy reports, analyze content, extract key information, and draft or rewrite text without leaving the editor. Explore topics further with integrated web search, and trace AI-generated answers back to their source pages for easy verification.
Choose from 10 leading AI providers, including OpenAI, Anthropic, Google Gemini, DeepSeek and more. Simply connect your preferred provider using your own API key (BYOK). Your requests go directly to your chosen provider, and your API keys remain securely encrypted on your computer. AI is entirely optional, and every other Monstera feature works without it.
Your keys are encrypted using Windows DPAPI and stored separately from application settings.
API keys remain hidden after entry. Replace or remove them anytime without exposing their contents.
If secure encryption is unavailable, Monstera refuses to store your keys in plaintext.
AI requests go directly to your chosen provider, with no intermediary. See what data is shared in the connection table.
Edit existing text directly in your PDF without recreating the document or disrupting its original layout. Simply click on a line to correct mistakes, update information, or rewrite content. Monstera intelligently modifies only the characters you change while preserving the surrounding text and formatting. It retains the original font wherever that font supports the new characters, automatically selecting the closest standard alternative when necessary.
You can also find and replace words or phrases throughout the document, making even extensive text revisions simple and efficient.
Edit words or entire lines while keeping the surrounding text intact.
Keep the original font or use the closest match when needed.
Find and replace words or phrases across your entire document.
Move, resize, recolour, or remove objects and images.
Unlike tools that simply cover sensitive text with a black rectangle, Monstera permanently removes the underlying content from the PDF. Automated tests verify that redacted text cannot be extracted again.
Redaction goes beyond visible text, removing associated hidden data. For added confidence, always review your redacted document before sharing.
Permanently deletes redacted content instead of simply hiding it behind a black box.
Clear associated form values, comments, thumbnails, and metadata.
Find and permanently redact matching text throughout your document.
Remove scripts, attachments, and potentially unsafe actions from your PDFs.
Convert Word, Excel and PowerPoint files into high-quality PDFs directly on your computer, completely offline. Monstera supports both older and modern Office formats, including documents containing Chinese, Japanese and Korean text.
Need a different format? Convert PDFs into editable Word documents, export content to Excel or PowerPoint, or turn pages into high-resolution images. Monstera also supports PDF/A for long-term archiving and PDF compression, with a before-and-after size comparison so you can see the savings before saving your file.
Convert Word, Excel and PowerPoint files into PDFs, entirely offline.
Choose from three conversion modes: editable text, page layout or text only.
Export to Excel, PowerPoint, PNG, JPEG or WebP with adjustable image resolution.
Create PDF/A-1b, 2b or 3b archives, or reduce file size with a savings preview.
Transform scanned documents into searchable, selectable PDFs with Monstera's built-in OCR. Supporting 14 languages, Monstera automatically detects image-only pages and extracts text you can search, select and copy. Standard OCR runs entirely offline, keeping your documents private and on your computer.
For handwritten content, Monstera integrates with Azure Document Intelligence and Anthropic to convert notes, forms and records into editable Word or Excel files. Review and correct recognized text before exporting to Excel for greater accuracy. Only the selected page or region is sent to your chosen provider, never the entire PDF.
Turn scanned pages into searchable PDFs without internet access or file uploads.
Recognize printed text in 14 languages, including English, Arabic, Chinese, Japanese and Korean.
Straighten pages, improve scan quality and create PDFs using your camera.
Convert handwritten content into editable files with AI-powered recognition.
Sign documents your way with Monstera. Draw your signature, choose from 15 professionally styled text signatures, or upload your own and place it anywhere on the page. For documents requiring stronger verification, use your digital certificate to securely sign or certify PDFs, including password-protected documents.
Go further with trusted timestamps that independently verify when a document was signed. Monstera also lets you validate existing digital signatures, save your signature for future use, and preserve signatures when saving signed documents. Whether you need a simple visible signature or certificate-based authentication, Monstera gives you the tools to handle both.
Digitally sign and certify PDFs using your own certificate, including protected documents.
Draw, type in 15 signature styles, or upload your own signature.
Verify signing times through trusted authorities without uploading your document.
Validate digital signatures, reuse your own, and save without breaking existing signatures.
PDFs can contain hidden scripts, automatic actions and potentially harmful content. Monstera treats every document as untrusted, processing it inside a secure Windows sandbox that isolates it from your personal files, system account and the rest of Windows.
Press F1 anywhere in Monstera and the Help centre opens on the article for the tool you are using. 144 articles explain how to do each thing Monstera can do, in numbered steps.
The Help centre is part of Monstera, so it works without an internet connection. Search with a few words, browse the articles suggested for the part of Monstera you are in, or let Show me point at the tool on screen. The same articles are in the online Help.
Monstera brings together proven open source engines for document processing, rendering, OCR, and conversion in a single Windows application. Each task is handled by the engine best suited for it. Click the dropdown to see details.
Licences for every component are listed on the third-party notices page.
See what you get with Monstera compared with other commercial PDF editors.
| What you get | Monstera | Typical paid PDF editor |
|---|---|---|
| Price | Free forever | Monthly or annual subscription |
| Account required | No | Often required |
| Open source | Yes, AGPL 3.0 | No |
| Edit existing text in place | Included | Paid feature |
| Redaction that removes content | Included | Usually a paid feature |
| OCR for scanned pages | Included, 14 languages | Usually a paid feature |
| Handwriting to Excel and Word | Included (with your Azure or Anthropic key) | Usually a paid feature |
| Digital signing with your certificate | Included | Varies by plan |
| AI assistant | Included, your own key | Usually a paid add on |
| Documents processed on your PC | Yes, by default | Cloud processing is common |
| Watermarks, page or file limits | None | Common on lower tiers |
| Platforms | Windows 10 and 11 | Varies |
Install from Microsoft Store. No account, no trial, no subscriptions.
