The best PDF annotator is the one that gives you full markup tools without uploading your documents, charging you, or stamping a watermark on the result. We tested nine popular annotators in 2026 across privacy, free limits, watermarks, and the depth of their markup tools. This guide ranks them, shows a comparison table, and explains exactly where each one wins so you can pick the right fit.
TL;DR: For free, private, unlimited markup, imisspdf is the best PDF annotator in 2026 — it runs highlight, comment, draw, shapes, stamps, and signature tools entirely in your browser with no upload, no account, no watermark, and no daily limit. Xodo is the best all-round free reader-annotator, PDF Expert is the best on iPad, and Adobe Acrobat remains the benchmark for deep professional annotation if privacy and price aren’t your priority.
How we ranked them
There are dozens of tools that let you scribble on a PDF, so we filtered on the things that actually decide whether an annotator is worth using day to day:
- Privacy / where files are processed. Does the tool upload your document to a server, or does it work on your own device? For the contracts, forms, and records people actually annotate, this matters more than any feature.
- Free limits. Is it genuinely free, or does it cap you after a couple of files, gate exports behind an account, or reserve the useful tools for a paid plan?
- Watermarks. Does the exported file carry a banner or stamp? A watermark you only discover after the work is done is a common trap.
- Markup depth. Highlight, underline, strike-through, freehand pen, shapes, text boxes, sticky comments, stamps, and signatures — how complete is the toolset?
- Platform fit. Web, desktop, phone, tablet, stylus support — the best tool depends on where you work.
We weighted privacy and free access most heavily, because feature parity across these tools is surprisingly high — almost all of them can highlight and comment. What separates them is the catch.
Comparison at a glance
| Tool | Processing | Free limit | Watermark | Best for |
|---|---|---|---|---|
| imisspdf | In your browser (no upload) | Unlimited | None | Privacy + unlimited free markup |
| Xodo | App / web | Generous free | None | All-round reader + annotator |
| Foxit | App / server | Limited free | None | Lightweight desktop annotation |
| PDF Expert | App (Apple) | Paid (trial) | None | iPad + Apple Pencil |
| Adobe Acrobat | Server / app | Limited free | None | Deep professional toolset |
| Sejda | Server upload | 3 tasks/hour | None | Light in-browser markup |
| Kami | Web / cloud | Limited free | None | Classroom annotation |
| Drawboard PDF | App (Windows) | Paid (trial) | None | Stylus on Windows tablets |
| PDF24 | Desktop / server | Unlimited (desktop) | None | Free offline desktop tools |
1. imisspdf — best for privacy + unlimited free markup
imisspdf is the closest thing to an annotator “without the catch.” The Annotate PDF tool covers the full everyday markup set — highlight, underline, strike-through, freehand pen, shapes, text boxes, sticky comments, stamps, and signatures — and it all runs entirely in your browser using WebAssembly. Your file is never uploaded, there’s no account, no watermark, and no daily limit.
That privacy model is the real differentiator. When you annotate a PDF on imisspdf, the document stays on your own device, which matters because the things people annotate — contracts, medical forms, financial statements, signed agreements — are often exactly what you don’t want on a stranger’s server.
It’s also more than an annotator: if you need to change the underlying text rather than mark on top of it, Edit PDF sits alongside, and there’s a dedicated PDF Reader for distraction-free reading before you mark anything up.
Strengths: zero upload for standard tools, no limits, no watermark, full markup toolset, works on phone and desktop, 12 languages. Trade-off: very large documents depend on your device’s memory rather than a server, and the AI tools use a bring-your-own-key model. For most people that’s a fair exchange for keeping documents private.
Best for: anyone who wants to highlight, comment on, or sign documents regularly and would rather not upload them — students marking up readings, professionals reviewing contracts, anyone filling and signing scanned forms. Because there’s no account and no limit, it’s also the lowest-friction option for a one-off: open the tool, mark up, download, done.
2. Xodo — best all-round free reader-annotator
Xodo is a long-time favorite for reading and annotating PDFs, with a generous free tier and a clean, touch-friendly interface across web and mobile. Its markup tools are comprehensive — highlights, ink, shapes, text, and comments — and it handles large documents smoothly, which is part of why it’s so popular for reading textbooks and long reports.
If you want a single app for both reading and marking up, with a genuinely generous free allowance, Xodo is an excellent pick. The main consideration is the same as any cloud app: its sync and storage features involve keeping files on its servers, so for the most sensitive documents an in-browser, no-upload tool is the safer default.
Best for: people who read and annotate a lot and want one polished app across desktop, web, and mobile.
3. Foxit — lightweight desktop annotation
Foxit is a lightweight Acrobat rival with strong annotation tools and good performance on desktop. Its comment and markup features are mature, and once installed it can annotate offline. The free tier is limited and the full feature set is paid, but for users who want a fast, installable annotator that doesn’t carry Acrobat’s weight or price, it’s a solid choice. The interface will feel familiar to anyone coming from Acrobat, which makes it an easy switch.
Best for: desktop users who want a fast, Acrobat-style annotator without the full Adobe subscription.
4. PDF Expert — best on iPad
PDF Expert is the standout annotator on Apple devices, especially the iPad with Apple Pencil. Its inking feels natural and low-latency, its reading experience is polished, and its markup tools are deep — handwriting, highlights, shapes, and a smooth signing flow. It’s subscription-based (with a trial), so it suits people who annotate heavily on an iPad and are willing to pay for the best stylus experience. On non-Apple platforms it isn’t an option, which is its main limitation.
Best for: iPad owners with an Apple Pencil who annotate by hand and want the most natural inking available.
5. Adobe Acrobat — the professional benchmark
Adobe Acrobat is the benchmark for deep, professional annotation — structured comment workflows, review collaboration where multiple people mark up the same file, and a vast toolset that goes well beyond highlighting. It’s subscription-priced and cloud-based, so it’s overkill for casual markup, but for teams running formal document reviews it remains the most capable option. If your annotation is part of a larger professional editing and collaboration workflow, Acrobat is built for exactly that.
Best for: teams and professionals running formal, multi-reviewer document markup at scale.
6. Sejda — light in-browser markup
Sejda offers real in-browser markup alongside its editing and conversion tools, with a free tier limited to a few tasks per hour and modest file-size caps. It’s a capable annotator for occasional light work — add a few highlights, a signature, or some notes — though heavier daily use pushes you toward its paid plan. It’s a reasonable middle ground if you want browser-based markup but also occasionally need its editing features.
7. Kami — classroom annotation
Kami is popular in education for annotating worksheets, marking up student submissions, and collaborating in the classroom. It integrates with school platforms and supports real-time collaboration, which is its real strength. The free tier is limited and the richer features are paid or school-licensed. For teachers and students it’s purpose-built; for general document markup outside a classroom, the more general-purpose tools fit better.
8. Drawboard PDF — stylus on Windows tablets
Drawboard PDF shines for stylus annotation on Windows tablets, with a natural inking experience designed around pen input. If you have a Surface or similar device and annotate by hand, it’s one of the best Windows options. It’s paid (with a trial), and like the other native apps it’s tied to its platform — so it’s a great pick specifically for Windows pen users and less relevant otherwise.
9. PDF24 — free offline desktop toolkit
PDF24 offers a very broad free toolkit including markup, and crucially a Windows desktop app that works fully offline. For users who want unlimited free annotation without any upload, PDF24’s desktop edition is a strong option — the web version does upload, but the desktop version keeps files on your machine. Its markup tools are functional rather than fancy, but the price (free) and the offline desktop processing make it a genuine privacy-friendly choice on Windows.
All four of these are viable depending on your platform and use case, but none combine unlimited + private + free + cross-platform the way the top pick does.
What the markup tools actually do
“Annotation” covers a handful of distinct tools, and knowing what each one is for helps you judge whether an annotator is complete:
- Highlight, underline, strike-through. The classic text markup. Highlight to flag important passages, underline for emphasis, strike-through to mark something for removal. These need a text layer to snap to — on a scanned image, they work as free shapes instead.
- Sticky comments / notes. A collapsible note pinned to a spot on the page. Ideal for review feedback, where you want to explain why something is flagged without cluttering the page.
- Text boxes. Type text directly onto the page — for filling a flat (non-interactive) form, adding a label, or writing a caption.
- Freehand pen / ink. Draw anything by hand. Essential for stylus users and for circling or arrowing parts of a diagram.
- Shapes. Rectangles, ellipses, lines, and arrows to point at, box, or connect elements.
- Stamps. Pre-made or custom marks like “APPROVED”, “DRAFT”, “CONFIDENTIAL”, or a date stamp — fast, consistent, and professional-looking.
- Signatures. Draw, type, or place a saved signature to sign a document without printing it.
A complete annotator offers all of these. Most of the tools above cover the common ones; the differences show up in the polish — how natural the inking feels, how easy it is to reposition a comment, whether stamps are customizable. imisspdf’s Annotate PDF tool includes the full set, and because it runs in your browser you can use every one of them without uploading the document.
Real tasks people use an annotator for
The right tool also depends on what you’re actually doing:
- Reviewing a contract. Highlight clauses, leave comments explaining concerns, and sign when agreed. Privacy matters most here — contracts are sensitive.
- Filling a flat form. Many forms aren’t interactive PDFs; they’re flat scans or exports. Text boxes and a signature let you complete them without printing. (For true interactive forms, a dedicated form filler is smoother.)
- Marking up a report for feedback. Sticky comments and highlights let you give structured feedback a colleague can act on.
- Annotating study material. Students highlight, underline, and add margin notes to readings and lecture slides.
- Signing a scanned document. Place a signature and date directly on the scan — no OCR needed, because you’re adding marks on top rather than editing text.
Match the tool to the task: for sensitive review work, prioritize a private, no-upload annotator; for handwritten study notes, a stylus app; for quick one-off markup, a no-account browser tool.
How to choose
- Want privacy + no limits + no cost? → imisspdf (in-browser) or PDF24 desktop (offline).
- Want one polished app for reading and markup? → Xodo.
- On an iPad with a Pencil? → PDF Expert.
- Running formal professional reviews? → Adobe Acrobat.
- Annotating worksheets in a classroom? → Kami.
The single biggest differentiator between these tools isn’t the markup features — most cover highlight, comment, draw, and sign. It’s where your file is processed. If the documents you annotate are sensitive, choose a tool that keeps them on your device. You can verify any “in-browser” claim yourself: open your browser’s developer tools, watch the Network tab, and confirm no upload happens when you annotate a PDF.
Annotating vs editing — pick the right job
A quick clarification that saves a lot of confusion. Annotating adds a layer on top: highlights, comments, stamps, signatures — the original content stays untouched. Editing changes the document’s own text and layout. If you want to mark up a report or sign a form, you want an annotator like Annotate PDF. If you want to correct the actual words, you want Edit PDF. For scanned documents the line is sharper: you can annotate a scan instantly, but editing its text first needs OCR. Many tasks combine both, which is why having editing and annotation in one place is convenient.
Recap
For most people in 2026, imisspdf is the best PDF annotator because it pairs a full markup toolset with genuine privacy — everything runs in your browser, with no upload, no account, no watermark, and no limit. Xodo is the best all-round free alternative, PDF Expert wins on iPad, and Adobe Acrobat leads for deep professional review. Match the tool to whether privacy, platform, or feature depth matters most to you.
Related guides
- Best Free PDF Reader 2026
- Best Smallpdf Alternatives 2026
- 10 In-Browser PDF Tools That Don’t Upload (2026)
Ready to mark up a document? Start with Annotate PDF, switch to Edit PDF when you need to change text, or just read first in the PDF Reader — all free, all in your browser.
Use Annotate PDF: Highlight, comment, and draw on PDFs. No signup, nothing uploaded.
Frequently asked questions
For most people the best PDF annotator in 2026 is imisspdf, because it covers the everyday markup tools — highlight, comment, draw, shapes, text boxes, stamps, and signatures — and runs entirely in your browser with no upload, no account, no watermark, and no daily limit. That combination is rare: most free annotators either cap your usage, upload your file to a server, or reserve the useful tools for a paid plan. imisspdf is the strongest default when you want full markup without a catch and your documents to stay on your own device. If you need a polished desktop reading-and-annotation app, Xodo and Foxit are excellent; if you want the deepest professional toolset and will pay, Adobe Acrobat is the benchmark; and if you live on an iPad, PDF Expert is hard to beat. The right pick depends on whether privacy, price, platform, or feature depth matters most to you.
Yes. imisspdf, Xodo, and PDF24 let you annotate and export without stamping a watermark on the output. The watermark problem is most common on smaller ad-supported tools and on the free tiers of otherwise-paid apps, so it is always worth testing a new annotator on a throwaway file first. imisspdf is explicit that there is no watermark, no signup, and no daily limit on any of its tools, which is the combination most people are actually looking for when they search for a free annotator — they want to highlight a report or sign a form without a banner across the page or a nag screen after two files. If a tool adds a watermark only on export, you usually will not discover it until you have already done the work, so check before you invest time.
It depends entirely on the architecture, not the brand. Many web-based annotators upload your file to a server, apply your markup there, and send it back — usually fine for ordinary documents, but a real consideration for contracts, medical forms, financial statements, or anything with personal data. The structurally safer annotators keep the file on your device. imisspdf processes its standard tools in your browser using WebAssembly, so the document is never uploaded; desktop apps like Xodo and Foxit can annotate fully offline once installed; and self-hosted tools keep files on infrastructure you control. For confidential documents, prefer one of these over any upload-based service, and verify the claim by opening your browser's Network tab and confirming no file upload request fires when you annotate.
Annotating adds a separate layer on top of the document — highlights, comments, shapes, stamps, drawings, or a signature — while leaving the original content untouched. Editing changes the document's own content: the actual text, the layout, the words on the page. The distinction matters because they are different jobs and often different tools. If you want to mark up a report, leave feedback, sign a form, or highlight passages, you want an annotator. If you want to correct a typo in the body text or change a figure, you want an editor. For scanned PDFs the line is sharper still: you can annotate a scan immediately, but editing its text first requires OCR to create a text layer. Many real tasks combine both — annotate a contract with a signature, then edit a clause — which is why the best tools offer editing and annotation side by side.
Yes, and there are two routes. The first is a dedicated mobile app — Xodo, Foxit, and PDF Expert all have strong touch-friendly apps, and PDF Expert in particular is a favorite on iPad with Apple Pencil support. The second is a browser-based annotator that runs inside a normal web page, which works on a phone or tablet the same way it works on a laptop: you open the tool, pick your PDF, and mark it up from the touchscreen. The browser route has the advantage of nothing to install and, with an in-browser tool, nothing uploaded. For light markup — a few highlights, a signature, a comment — either route is quick. For heavy, precise annotation on a large document, a stylus on a tablet app tends to feel more comfortable than a finger on a phone screen.
Not with every tool. Several annotators — imisspdf, PDF24, and the free web tiers of some others — let you start marking up immediately with no signup. Others require an account before you can export, save, or unlock the full toolset, and the heavier professional apps (Adobe Acrobat, PDF Expert) are subscription-based. If you only need to annotate occasionally, a no-account in-browser tool is the lowest-friction option: you open the page, do the work, and download, with nothing tying the document to a profile or cloud. If you annotate constantly across devices and want synced files, cloud accounts and paid apps offer convenience in exchange for storing your documents on their servers. Match the friction to how often you actually annotate.
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