Start with the thing most people do not realise: you can already fill in and sign a PDF with software on your computer right now. Any modern browser can open a PDF, fill its form fields, add a signature and save the result. Preview on a Mac can merge, reorder, rotate and annotate. Nothing needs installing and nothing needs uploading.
"Edit a PDF" covers several different jobs, and the right free tool depends entirely on which one you mean.
| Task | Free answer | Notes |
|---|---|---|
| Fill and sign a form | Your browser, or Preview on Mac | Already installed |
| Merge, split, rotate | Stirling PDF, or Preview on Mac | Stirling runs locally |
| Edit the actual text | LibreOffice Draw | Layout will shift; expect cleanup |
| Compress | Stirling PDF, or re-export | Images are usually the weight |
| OCR a scan | OCRmyPDF, Stirling PDF | Makes scans searchable |
| Everyday reading and markup | PDFgear, Xodo | Free, full-featured readers |
Stirling PDF — the open-source Swiss army knife
Best for: everything except editing body textStirling PDF is an open-source toolkit covering close to fifty operations: merge, split, rotate, reorder, compress, convert to and from images and Office formats, add watermarks and page numbers, OCR scanned documents, remove passwords, fill forms, sign, and redact.
Its important property is that it runs on your own machine. You install it locally (via Docker, or a standalone build) and it never sends your documents anywhere. For anything containing a contract, an ID, a medical record or a bank statement, this distinction is the whole point.
Where it falls short: setup is the price. Running a Docker container is trivial if you have done it before and a genuine obstacle if you have not. There is a hosted demo, but using it for sensitive documents defeats the purpose. It also does not do free-form text editing of existing PDF content.
LibreOffice Draw — for actually editing the text
Best for: changing words inside an existing PDF, freeThis is the part nearly every "free PDF editor" list gets wrong. Most free tools let you annotate a PDF — add a text box on top, draw, highlight. Very few let you change the text that is already there. LibreOffice Draw does.
Open a PDF in Draw and its contents become editable objects. Click into a paragraph, change the words, move things, save back to PDF. It is free, offline, and installed as part of the LibreOffice suite.
Where it falls short: a PDF is a description of marks on a page, not a document with structure, so what you get is a best-effort reconstruction. Text is often split into separate blocks per line, so editing a sentence can break the paragraph. Fonts that were not embedded get substituted and the layout shifts. Complex documents come apart badly.
Realistic expectation: excellent for fixing a typo, a date or a name. Painful for rewriting a paragraph. Hopeless for restructuring a designed document — for that, find the original file it was exported from.
PDFgear and Xodo — full-featured free readers
Best for: day-to-day reading, annotating and light editingPDFgear is a free desktop application covering reading, annotating, merging, splitting, converting, form filling and signing, with no account and no watermark. Xodo is similar with a strong mobile and web presence, and is particularly good for annotation on a tablet.
Where they fall short: both are commercial products that are free rather than open source, which means the terms are a business decision that can change. Cloud features involve uploading. Neither does serious text editing. For most people these are nonetheless the most pleasant everyday replacement for Acrobat Reader.
What you already have installed
Before installing anything, check whether the job is already done:
- Any browser — opens PDFs, fills form fields, saves the filled copy. Chrome and Edge also let you add a drawn signature.
- Preview (macOS) — merges PDFs by dragging pages between windows, reorders, rotates, annotates, signs with a trackpad-drawn signature, and exports compressed. It quietly does most of what people pay Acrobat for.
- Word — opens PDFs and converts them to editable documents. Layout fidelity varies from decent to terrible, but for a text-heavy document it often works.
- Print to PDF — built into Windows and macOS. Flattens forms, merges via printing, and strips problem layers.
A warning about free online PDF sites
Search "merge PDF" and you get dozens of sites that will happily process your file. Most are legitimate businesses. But it is worth understanding what you are agreeing to: your document is uploaded to someone else's server, processed there, and stored for some period you are trusting them about.
For a restaurant menu, fine. For an employment contract, a passport scan, a tax return or a medical record, you have just handed a complete copy to a third party whose retention policy you did not read and whose security you cannot verify. Free services are funded somehow, and "we delete after an hour" is a promise, not a mechanism.
The practical rule: if the document contains anything you would not email to a stranger, use a tool that runs on your own machine. Stirling PDF locally, LibreOffice, Preview, or your browser. This is the same reasoning behind the tools on this site running in your browser rather than on a server.
So which one?
Fill in and sign a form: your browser. It is already open.
Merge, split, compress, convert, OCR: Stirling PDF, installed locally. Preview if you are on a Mac and the job is simple.
Change the text inside a PDF: LibreOffice Draw, with realistic expectations. Better still, find the original document.
A pleasant daily reader: PDFgear or Xodo.
The document is sensitive: nothing that uploads. No exceptions worth making.
What Acrobat Pro still does better
Three things genuinely justify the subscription for some people. Reliable redaction that actually removes the underlying data rather than drawing a black box over it — getting this wrong has ended careers. PDF/A archival and accessibility tagging for compliance requirements. And preflight for commercial print, where a printer will reject a file for colour profile or bleed problems that Acrobat can diagnose and free tools cannot.
If none of those describe your work — and for most people none do — the free stack above covers it.
Frequently asked questions
Can I edit a PDF for free?
Yes. LibreOffice Draw opens PDFs as editable objects and can save back to PDF, which is the only free desktop option that reliably edits existing text. Expect layout shifts on complex documents — it works best for small corrections.
How do I sign a PDF without Acrobat?
Open it in your browser — Chrome and Edge both support drawing a signature and saving the result. On a Mac, Preview does it with a signature drawn on the trackpad or captured with the camera. Neither requires an account or an upload.
Are free online PDF tools safe?
They upload your document to a server you do not control. Most operators are legitimate, but you are trusting an unverifiable retention and security policy. For contracts, IDs, medical or financial documents, use something that runs on your own machine instead.
How do I merge PDFs for free?
On a Mac, open one in Preview, show the thumbnail sidebar, and drag the other PDF into it. On Windows, Stirling PDF running locally does it, as does PDFgear. Both avoid uploading anything.
How do I make a PDF smaller?
Images are almost always the weight. Compressing them before creating the PDF gives the best result. For an existing file, Stirling PDF has a compression tool, and exporting from Preview with the Reduce File Size filter works on a Mac.
Why is my edited PDF formatting broken?
A PDF describes marks on a page, not a structured document. Editors reconstruct text blocks by guessing, and non-embedded fonts get substituted. Small edits usually survive; rewriting paragraphs usually does not. Editing the original source document is always better.