100% Client-Side PDF / Image / Text Tools: The Honest 2026 Guide
A truly 100% client-side tool runs entirely in your browser or on your computer, without uploading your files to a remote server. The strongest options in 2026: PDF-XChange Editor, Master PDF Editor, LibreOffice Draw (PDF); Photopea, Squoosh, Upscayl, GIMP, Krita (image); Diffchecker, VS Code, Notep
Quick answer
A truly 100% client-side tool runs entirely in your browser or on your computer, without uploading your files to a remote server. As of 2026, the strongest options in each category are:
- PDF: PDF-XChange Editor (Windows desktop, the strongest free client-side PDF editor), Master PDF Editor (Windows / Linux desktop), LibreOffice Draw (cross-platform, open-source), and Sejda Web in client-side mode (browser-based).
- Image: Photopea (browser-based, runs locally, the closest free Photoshop replacement), Squoosh (Google's image compressor, fully browser-local), and Upscayl (open-source AI image upscaler, fully local).
- Text: Diffchecker (browser-based diff tool), JSON viewers and formatters in the browser, and your operating system's built-in text editor.
Three honest distinctions before the details:
- "Runs in your browser" is not the same as "client-side." Many browser-based tools (iLovePDF, Smallpdf, Sejda default mode) upload your files to a remote server for processing. Truly client-side tools do the work on your machine and never send the file anywhere.
- Truly client-side tools often require more setup than upload-based browser tools. The privacy gain is real; the convenience is slightly lower.
- Some tools are partially client-side — they process locally but also call optional remote services (for example, OCR or AI features). Read each tool's documentation to confirm.
What "100% client-side" actually means
When a tool is genuinely client-side:
- Your file never leaves your computer.
- Processing happens in your browser (via JavaScript, WebAssembly, or similar) or as a desktop app on your machine.
- The tool does not require an internet connection for the actual processing, only for the initial page load (browser tools).
- The tool does not require an account.
- The tool's privacy policy does not need to be trusted with your file content.
When a tool is NOT client-side (even if it runs in your browser):
- Your file is uploaded to the tool's server.
- Processing happens on the server.
- The result is downloaded back to your browser.
- The tool's privacy policy governs how your file is handled.
This article only covers the first category — tools that genuinely do not upload your files.
How to verify a tool is truly client-side
Five quick checks:
- Open the browser's developer tools (F12 in most browsers) and look at the Network tab. Process a file. If you see requests uploading file data to a remote server, the tool is not client-side.
- Read the privacy policy. Truly client-side tools often explicitly state that files do not leave your computer.
- Disconnect from the internet and try again. A truly client-side tool will still work (after the initial page load for browser tools; desktop tools work fully offline).
- Look for source code on GitHub. Truly client-side tools are often open-source, with verifiable code.
- Check for WebAssembly or JavaScript that handles the file in-browser. Modern client-side tools use WebAssembly (often compiled from C++ or Rust) to handle complex operations like PDF editing in the browser.
Client-side PDF tools
1. PDF-XChange Editor — the strongest client-side PDF editor
What it does: A Windows-only PDF editor with full text editing, annotation, form filling, OCR, page manipulation, and digital signatures. The free version includes most features.
Client-side? Yes — runs as a desktop application on Windows. Files never leave your computer.
Best for: Windows users who need a real PDF editor without paying. The closest free alternative to Adobe Acrobat Pro for editing with font preservation.
2. Master PDF Editor — cross-platform alternative
What it does: A freemium desktop PDF editor for Windows and Linux. Text editing, image editing, form creation, and OCR with paid tier.
Client-side? Yes — desktop application.
Best for: Windows or Linux users who want a cross-platform alternative.
3. LibreOffice Draw — the cross-platform open-source option
What it does: A free, open-source desktop application for Windows, macOS, and Linux. Opens and edits PDFs.
Client-side? Yes — desktop application. Fully offline.
Best for: Anyone on any platform who wants a free, open-source PDF editor.
4. Photopea — the browser-based image and PSD editor that also handles PDFs
What it does: A free, browser-based image editor (Photoshop alternative) that also opens and edits PDFs. Runs entirely in the browser.
Client-side? Yes — Photopea runs in the browser and processes files locally. No upload required.
Best for: Users who want a browser-based editor that does not upload.
5. PDF.js (the underlying library)
What it does: Mozilla's open-source PDF rendering library. It is the engine behind Firefox's built-in PDF viewer and many other client-side PDF tools.
Client-side? Yes — fully JavaScript, fully client-side.
Best for: Developers building client-side PDF tools. Most users interact with PDF.js through Firefox or other apps built on top of it.
6. PDF-lib — JavaScript PDF manipulation library
What it does: An open-source JavaScript library for creating and modifying PDFs in the browser or Node.js.
Client-side? Yes — runs in the browser.
Best for: Developers building client-side PDF applications.
7. Sejda Web in client-side mode
What it does: Sejda offers many PDF operations in the browser. Some operations run client-side; others upload to a server.
Client-side? Partially. Look for the "Local processing" indicator on each operation.
Best for: Users who want a browser-based tool and check the local-processing indicator.
Client-side image tools
8. Photopea — the best free client-side image editor
What it does: A free, browser-based Photoshop alternative with full PSD support, layers, masks, filters, and an expanding set of AI features. Runs entirely in the browser.
Client-side? Yes — processes files locally. No upload required.
Best for: Anyone who wants Photoshop-class control in the browser without uploading files.
9. Squoosh — Google's client-side image compressor
What it does: A free, browser-based image compressor and converter from Google Chrome Labs. Supports JPEG, PNG, WebP, AVIF, and other formats with side-by-side quality comparison.
Client-side? Yes — processing happens in the browser using WebAssembly.
Best for: Image compression with quality control. The strongest free image compressor that does not upload.
10. Upscayl — open-source AI image upscaler
What it does: A free, open-source desktop application that uses AI to upscale and enhance images. Runs on Windows, macOS, and Linux.
Client-side? Yes — fully offline desktop app.
Best for: AI image upscaling without uploading to a cloud service.
11. GIMP — the strongest free client-side desktop image editor
What it does: A free, open-source desktop image editor with Photoshop-class features. Runs on Windows, macOS, and Linux.
Client-side? Yes — desktop application.
Best for: Desktop image editing without uploading.
12. Krita — the best free client-side painting app
What it does: A free, open-source painting and illustration application. Strong on digital painting, brush engines, and animation.
Client-side? Yes — desktop application.
Best for: Artists and illustrators who want a powerful painting app that runs locally.
13. remove.bg desktop equivalent (no real desktop client)
What it does: remove.bg is browser-based but uploads the image to a server. There is no fully client-side equivalent of remove.bg with the same accuracy. For privacy-respecting background removal, use desktop Photoshop / GIMP with manual masking.
Client-side text tools
14. Diffchecker — browser-based diff tool
What it does: A free, browser-based diff tool that compares two text files and shows the differences. Also supports image and PDF diffs.
Client-side? Yes — the diff is computed in the browser. No upload.
Best for: Comparing two versions of a text file without uploading.
15. JSON viewers and formatters
Many free JSON tools run entirely in the browser:
- JSON Viewer by daviddr 93 (browser extension).
- JSON Formatter by Nikhil Vallishayee (browser extension).
- JSON Crack — visualises JSON as a graph in the browser.
Most JSON tools on the web run client-side because JSON parsing in JavaScript is straightforward. Verify the privacy policy before pasting sensitive data.
16. Code beautifiers and validators
Many free code-formatting and validation tools run client-side:
- JSONLint — has both client and server modes; check the URL.
- Prettier Playground — formats code in the browser.
- regex101 — runs entirely client-side for testing regular expressions.
17. Markdown editors
- StackEdit — a free, browser-based Markdown editor that saves to local storage or cloud storage of your choice.
- Dillinger — a free Markdown editor that runs in the browser.
Both work entirely in the browser. Files do not leave your computer unless you explicitly export or sync to a cloud service.
18. Plain text editors
Your operating system comes with a text editor. For more capable text editing, consider:
- VS Code — free, open-source, runs locally. Excellent for code and Markdown.
- Sublime Text — paid but very fast.
- Notepad++ — free, Windows-only.
- BBEdit — paid, macOS-only.
- Kate / KWrite — free, Linux.
These are all fully offline and fully local.
Quick comparison table
| Tool | Category | Platform | Truly client-side | Open source |
|---|---|---|---|---|
| PDF-XChange Editor | PDF editor | Windows | Yes | No (free with paid tier) |
| Master PDF Editor | PDF editor | Windows / Linux | Yes | No (free + paid) |
| LibreOffice Draw | PDF editor | Cross-platform | Yes | Yes |
| Photopea | Image + PDF editor | Browser | Yes | No (free) |
| Squoosh | Image compressor | Browser | Yes | Yes (Chrome Labs) |
| Upscayl | AI image upscaler | Cross-platform desktop | Yes | Yes |
| GIMP | Image editor | Cross-platform | Yes | Yes |
| Krita | Digital painting | Cross-platform | Yes | Yes |
| Diffchecker | Text diff | Browser | Yes | No (free + paid) |
| VS Code | Text editor | Cross-platform | Yes | Yes (core) |
| Notepad++ | Text editor | Windows | Yes | Yes |
How to choose
- I need a PDF editor with font preservation and editing: PDF-XChange Editor on Windows, or LibreOffice Draw cross-platform.
- I want a browser-based image editor: Photopea.
- I want to compress an image: Squoosh.
- I want to AI-upscale an image: Upscayl.
- I want a desktop image editor: GIMP.
- I want a digital painting app: Krita.
- I want to compare two text files: Diffchecker.
- I want a code editor: VS Code.
- I want a Markdown editor: StackEdit or Dillinger.
Common gotchas to avoid
- Assuming "browser-based" means "client-side." Many browser-based tools upload to a server. Verify with developer tools before uploading sensitive content.
- Assuming "free" means "open source." Many of the tools above are free but not open source. They may be trustworthy but you cannot verify the code.
- Trusting AI features to be local. Some tools process most things locally but call remote services for AI features (OCR, voice synthesis, etc.). Read each tool's documentation.
- Assuming desktop tools are private. Desktop tools may still phone home for telemetry or updates. Most have a "disable telemetry" option in settings.
- Forgetting that browser tools cache your data. Browser-based tools may leave your file in browser cache or local storage. Clear cache after use if privacy matters.
- Using the wrong tool for the job. Some browser-based tools claim to be client-side but actually require a small server roundtrip. Verify with network inspection.
Frequently asked questions
What does "100% client-side" mean?
It means the tool runs entirely in your browser or on your computer, without uploading your file to a remote server. Processing happens locally; the tool never sees your file.
How do I know if a browser tool is truly client-side?
Open the browser's developer tools (F12), go to the Network tab, and process a file. If you see requests uploading file data to a remote server, the tool is not client-side. If you see no such requests, the tool is processing locally.
Are client-side tools slower than server-side tools?
Sometimes. Server-side tools can use more powerful hardware and run faster for complex operations like OCR. Client-side tools run on your machine, so performance depends on your hardware. For most everyday tasks, the difference is negligible.
Can I use client-side tools offline?
After the initial page load, browser-based client-side tools typically work offline. Desktop client-side tools work fully offline after installation.
Do client-side tools collect telemetry?
Most desktop client-side tools collect some anonymous telemetry by default. Most have an option to disable telemetry in settings. Browser-based tools may include analytics in the page itself.
What is the best free client-side PDF editor?
PDF-XChange Editor on Windows, LibreOffice Draw cross-platform. Both are free, run locally, and provide real PDF editing with font preservation.
What is the best free client-side image editor?
Photopea (browser-based, runs locally) or GIMP (desktop). For AI image upscaling, Upscayl.
What is the best free client-side text editor?
VS Code (cross-platform), Notepad++ (Windows), Kate (Linux), or TextEdit (macOS).
Can I trust open-source client-side tools more than closed-source ones?
Open-source tools are auditable. Closed-source tools require trust in the vendor. For sensitive work, open-source is generally the safer choice.
Are WebAssembly-based tools truly client-side?
Yes — WebAssembly runs in the browser. A tool that uses WebAssembly for processing is doing the work locally in your browser. No data leaves your computer.
What about WebAssembly tools that call remote AI APIs?
That is a hybrid model. The base processing is local, but AI features call remote services. If you opt out of the AI features, the tool is fully client-side.
Key takeaways
- "Client-side" means the file never leaves your computer. Many "browser-based" tools are not actually client-side.
- PDF-XChange Editor, Master PDF Editor, and LibreOffice Draw are the strongest client-side PDF editors.
- Photopea and Squoosh are the strongest client-side browser-based image tools.
- Upscayl, GIMP, and Krita are the strongest client-side desktop image tools.
- Diffchecker and VS Code are strong client-side text tools.
- Verify with developer tools that a browser-based tool does not upload your file.
- Open-source tools are auditable. For sensitive work, prefer open-source client-side tools.