Document Viewer. Open & Preview Any File Online
One drop zone for everything. Add a PDF, CSV, Excel workbook, text file, Markdown, EPUB, RTF or image and the viewer works out the format for you and renders a faithful preview right in your browser: page through a PDF, scroll a spreadsheet, read rendered Markdown or an e-book, all without an app, an account or an upload.
What is the document viewer?
The Document Viewer opens almost any document in your browser. Drop a PDF, CSV, Excel, text, Markdown, EPUB, RTF or image file and it auto-detects the format, showing paged PDFs, scrollable spreadsheets, rendered Markdown and more. Previews are lazy-loaded and you can download the original. Fully private. Nothing is uploaded.
The GigAI Document Viewer is the catch-all opener for when you have a file and just need to see what's inside it, without hunting for the right app, buying a licence, or uploading a private document to some website. Drop a file onto the single universal drop zone (or click to browse, or paste one from your clipboard) and the viewer detects the format from its contents and extension, then renders it with the appropriate previewer entirely on your device. A PDF opens as a crisp, paged pdf.js canvas you can move through page by page. A CSV or Excel workbook (.xlsx) opens as a clean, scrollable grid, with a sheet switcher for multi-sheet workbooks. Markdown is rendered to formatted HTML rather than shown as raw asterisks, plain text appears with a live character/word/line count, JSON is pretty-printed and monospaced, an EPUB opens as a real reflowing e-book rendition with prev/next paging, RTF is converted to formatted HTML for display, and images are shown fitted to the frame. When a format can't be previewed, you still get a tidy fallback with the file's name, size and a one-click download rather than a broken page. Because every previewer runs in the browser and each heavy library is loaded only when its format is actually shown, opening a file is fast and completely private: nothing is transmitted, stored or logged, so confidential PDFs, financial spreadsheets and unreleased drafts are safe to open here. Two honest boundaries worth stating up front: this is a viewer, not an editor or a converter. It shows the file and lets you download the original as-is, but it does not modify, convert or re-export it (there are dedicated GigAI tools for that). And it can only render what a file actually contains: a scanned or image-only PDF will display as page images with no selectable text, and legacy binary formats such as old.doc or.ppt aren't previewable in the browser here.
- Difficulty:
- Easy
- Typical time:
- ~15s
- Processing:
- 100% browser processing
Last updated
How to use the document viewer
- 1
Drop or choose a file
Drag a document onto the drop zone, click to browse, or paste one from your clipboard. PDF, CSV, XLSX, TXT, MD, JSON, EPUB, RTF and images are all accepted.
- 2
Let it auto-detect
The viewer identifies the format from the file's contents and extension and loads the matching previewer. You don't have to pick a type.
- 3
Read, page or scroll
Move through a PDF page by page, scroll a spreadsheet grid, switch sheets in a workbook, page through an EPUB, or read rendered Markdown: whatever the file needs.
- 4
Download or open another
Download the original from the preview chrome if you want to keep it, or reset the viewer and drop a different file to open it just as fast.
What Document Viewer includes
One viewer for every file
PDF, CSV, Excel (.xlsx), text, Markdown, JSON, EPUB, RTF and common images all open through a single drop zone. No need to find the right app or switch between tools for each format.
Automatic format detection
Drop a file and the viewer works out what it is from its contents and extension, then picks the matching previewer for you. There's nothing to configure and no format to choose.
Format-aware previews
Each type is shown the right way: PDFs paginate, spreadsheets become scrollable grids with a sheet switcher, Markdown renders to formatted text, EPUBs reflow as an e-book, and images fit the frame.
Fast and lazy-loaded
Each heavy previewer library (pdf.js, SheetJS, epub.js) is loaded only when its format is actually opened, so the page stays light and a file appears within moments of dropping it.
Download the original
Grab the original file straight from the preview chrome with one click. Even unsupported formats get a tidy fallback card with the name, size and a download button instead of a broken view.
100% private, in-browser
Every file is opened and rendered on your device. Nothing is uploaded, stored or logged, so confidential PDFs, financial spreadsheets and unreleased drafts are safe to open here.
Why use our document viewer
Skip installing apps
No PDF reader, spreadsheet suite or e-book app required. If you can open a browser tab, you can open the file. Handy on a locked-down work machine or a borrowed computer.
Open sensitive files safely
Because the viewer never uploads anything, you can inspect a confidential contract, a payroll spreadsheet or an unreleased draft without it ever leaving your machine.
Quickly check what's inside
Received a mystery attachment or an unlabelled export? Drop it in to see its contents at a glance before deciding what to do with it, convert it, edit it elsewhere, or discard it.
One habit for many formats
Instead of remembering which app opens which extension, use one drop zone for PDFs, spreadsheets, Markdown, e-books and images alike.
Built for the way you work
From quick one-off fixes to daily workflows, see how people put this tool to use.
- Everyday / General
Open a mystery attachment
Someone emailed a file and you don't have the right app installed. Drop it into the viewer to see what's inside before deciding whether to keep, convert or delete it.
- Analyst / Finance
Peek at a spreadsheet fast
Open a CSV export or an Excel workbook as a scrollable grid, flip between sheets and check the columns without launching a heavyweight spreadsheet app.
- Reader / Student
Read an EPUB or PDF anywhere
Open an e-book or a PDF study guide in the browser on a machine with no reader installed, and page through it comfortably.
- Developer / Docs
Preview Markdown and JSON
See a README render exactly as it will look, or pretty-print a JSON payload to inspect its structure, without pasting private content into an online box.
Supported formats
Accepts PDF, CSV, XLSX, TXT and MD, and produces Original file, all processed locally in your browser.
- CSV
- XLSX
- TXT
- MD
- JSON
- EPUB
- RTF
- PNG
- JPG
- Original file
Frequently asked questions
Recommended tools
Document Comparer
Compare two documents and see exactly what changed. Upload two PDF, Word, RTF, text or Markdown files and get a color-coded diff (additions in green, removals in red) with an added/removed count, all in your browser. Nothing is uploaded.
CSV Editor
Open, edit and clean CSV files in your browser as a real spreadsheet, fix cells, add or delete rows and columns, sort, find, and export to CSV, JSON or Excel. Nothing is uploaded.
Markdown to PDF
Write or paste Markdown and export a clean, printable PDF in your browser. Live GitHub-flavoured preview with headings, tables, code blocks and task lists, page size, margins and theme included. Nothing is uploaded.
PDF to Word
Turn a PDF into an editable Microsoft Word (.docx) document, text extracted into clean, editable paragraphs, entirely in your browser with no upload.
EPUB Viewer
Open and read any.epub book right in your browser, a paginated, book-like reader with a table-of-contents sidebar, adjustable font size and light, sepia or dark themes. Nothing is uploaded. Your book never leaves your device.
RTF Viewer
Open and read.rtf (Rich Text Format) files right in your browser. Drop or paste an RTF document and see its formatted text (bold, italic, underline and paragraphs) then export clean HTML or plain text. Nothing is uploaded.
Common problems, solved
Hit a snag? Here are quick fixes for the issues people run into most.
My PDF opens but I can't select any text.
The PDF is a scan or an image-only export, so its pages are pictures with no underlying text layer. The viewer displays those page images faithfully. To get selectable text you'd need to run the file through an OCR tool first.
My file shows the fallback card instead of a preview.
The format isn't one the viewer can render in-browser, legacy binary.doc /.ppt and some niche types fall here. You can still download the original from the card, for.doc, try the Word-to-PDF tool, and for spreadsheets export to.xlsx or.csv first.
I edited the file in the viewer but changes didn't save.
This is a read-only viewer, not an editor. Grids, text and PDFs are shown for viewing only and nothing you type is saved. Use the dedicated CSV Editor, PDF Editor or Markdown tools when you need to make and keep changes.
A very large file is slow to open.
Big PDFs render page by page and large workbooks parse every row, both of which take a moment. Give it a few seconds. If a file is enormous, opening a smaller export or a single sheet will be faster.
Get the most out of it
You don't need to pick a format, just drop the file and the viewer detects it. Paste from the clipboard works too.
For a multi-sheet Excel workbook, use the sheet switcher above the grid to move between tabs.
Markdown is rendered, not shown raw: perfect for previewing a README exactly as it'll appear before you publish it.
Need to change the file, not just look at it? Reach for the CSV Editor, PDF Editor or a converter. This tool is view-only by design.
A scanned PDF will open as page images. Run it through OCR first if you need to select or copy its text.
What's new
Recent updates and improvements to the document viewer.
Initial release: a universal in-browser viewer that auto-detects and previews PDF, CSV, Excel, text, Markdown, JSON, EPUB, RTF and image files, with a one-click download of the original and a tidy fallback for unsupported types.
Added a sheet switcher for multi-sheet Excel workbooks and a live character/word/line count on the plain-text preview.
Improved handling of scanned and image-only PDFs with a clear 'no selectable text' notice, and refined the fallback card for legacy binary formats.
Keep exploring
Problems we solve
Definitions
From the blog
- How to Convert Excel to PDF: Keep Your Spreadsheet Readable When You Share It
- The EPUB Format Explained: What It Is, How to Read It, and How to Convert It
- How to Convert Markdown to PDF: Turn Plain Text Into a Polished Document
- How to Add Page Numbers to a PDF: Positions, Formats, and Ranges Explained
- How to Compress Files for Email: PDFs and Images Under 25 MB
Explore categories
Compare formats
Common tasks
Your privacy is built in
Every file you open is read and rendered entirely in your browser: nothing is ever uploaded to a server. PDFs are drawn with pdf.js, spreadsheets parsed with SheetJS, Markdown rendered with marked, EPUBs opened with epub.js and RTF converted with a built-in parser, all on your device. Each library loads only when its format is shown, and nothing is stored, logged or transmitted. That makes it safe to open confidential PDFs, financial spreadsheets and unreleased drafts here. Close the tab and every trace is gone.
- Runs in your browser
- No uploads
- Nothing stored
Ready to try the document viewer?
Free, private and instant. Document Viewer runs right in your browser.