DEV Community: Shakeel Skl

5 PDF Tools That Never Upload Your Files

Shakeel Skl — Mon, 30 Mar 2026 20:38:34 +0000

We've all been there. You need to merge two PDFs quickly, so you Google "merge PDF free", click the first result, upload your documents — and then realize you just sent potentially sensitive files to some random server in another country.

For most people, that's fine. But what if those PDFs contain:

A signed contract with client details
A bank statement
A confidential business proposal
Medical records
Legal documents

Suddenly that "free" tool doesn't feel so free.

The Problem With Most Free PDF Tools

Most online PDF tools work the same way:

You upload your file to their server
Their server processes it
You download the result
Your file sits on their server (for how long? who knows)

Some tools are transparent about this. Many aren't. And even the honest ones — you're trusting their security, their data retention policies, and that they won't sell or misuse your data.

There's a better way.

Browser-Based PDF Processing — How It Works

Modern browsers are powerful enough to process PDF files entirely locally using JavaScript libraries like PDF.js and pdf-lib. This means a well-built tool can:

Read your PDF file in memory
Process it (merge, split, compress, whatever)
Give you the result to download

All without your file ever touching a server.

Your file goes: device → browser → device. That's it.

5 PDF Tools That Work This Way

All of these tools are available free at solvebar.com — no login, no upload, no tracking.

1. PDF Merger

🔗 solvebar.com/tools/pdf-merger

Combine multiple PDF files into one. Drag to reorder before merging. The entire operation runs in your browser — useful when you need to combine contracts, reports or scanned documents without exposing their contents.

When you need it: Combining a cover letter and portfolio into one file before sending a job application. Merging monthly bank statements into one annual document.

2. PDF Splitter

🔗 solvebar.com/tools/pdf-splitter

Extract specific pages or split a PDF into individual pages. Set custom page ranges. Download split files individually or all at once as a ZIP.

When you need it: A 50-page contract where you only need to share pages 12-15 with a client. Extracting one invoice from a batch PDF.

3. PDF Compressor

🔗 solvebar.com/tools/pdf-compressor

Reduce PDF file size by removing embedded metadata and optimizing object streams. No quality slider that secretly re-renders your document through a server.

When you need it: A scanned document that's 15MB and needs to be emailed. Reducing file size before uploading to a portal with size limits.

4. PDF Watermark

🔗 solvebar.com/tools/pdf-watermark

Add custom text watermarks to all pages — control font, size, color, opacity and rotation. Mark documents as DRAFT, CONFIDENTIAL or SAMPLE before sharing.

When you need it: Sending a proposal to a client before the contract is signed. Sharing a sample report while protecting the full version.

5. PDF Form Filler

🔗 solvebar.com/tools/pdf-form-filler

Fill in PDF form fields directly in your browser — text fields, checkboxes, radio buttons and dropdowns. Download the completed form as PDF.

When you need it: Government forms, tax documents, application forms. These almost always contain personal information you really don't want sitting on a stranger's server.

The Offline Bonus

Because these tools run entirely in the browser, if you install solvebar.com as a PWA (Progressive Web App), they work completely offline. No internet connection required after the first load.

On Chrome: address bar → install icon → Add to Home Screen.

Why Solvebar Is Different

✅ Most free tools upload your file to a server — Solvebar doesn't

✅ Most free tools require login — Solvebar never does

✅ Most free tools don't work offline — Solvebar works as a PWA

✅ Most free tools have data retention risk — Solvebar has none

Who This Matters Most To

Lawyers handling client documents
Accountants working with financial records
HR professionals processing personal employee data
Freelancers sharing contracts and proposals
Anyone in the EU where GDPR makes data handling a legal matter
Privacy-conscious individuals who just don't want their files on someone else's server

Conclusion

The next time you need to process a PDF, ask yourself one question before uploading: do I know where this file is going?

If the answer is no — or if the document contains anything sensitive — use a tool that keeps your files on your device.

All five tools above are free, require no login, and process everything locally in your browser.

👉 solvebar.com/tools/pdf-merger

👉 solvebar.com/tools/pdf-splitter

👉 solvebar.com/tools/pdf-compressor

👉 solvebar.com/tools/pdf-watermark

👉 solvebar.com/tools/pdf-form-filler

All tools on SolveBar run entirely in your browser. No files are uploaded, no data is tracked, no login is required.

Building browser-only PDF tools — merge, split, and canvas builder without touching a server

Shakeel Skl — Mon, 23 Mar 2026 10:28:22 +0000

Most PDF processing tools have a fundamental architecture problem: they upload your files to a server to do the work.

This makes sense historically — PDF manipulation used to require server-side processing. But modern browser APIs have made that unnecessary for the majority of document workflows. pdf-lib, pdfjs-dist, and Fabric.js give you everything you need to merge, split, and build PDFs entirely client-side.

Here's how I built three PDF tools without a single file upload.

The core libraries

pdf-lib — JavaScript PDF creation and modification, runs in browser and Node. Handles merging, splitting, page manipulation, metadata. The API is clean:

const { PDFDocument } = await import("pdf-lib");

// Merge
const merged = await PDFDocument.create();
for (const file of files) {
  const src     = await PDFDocument.load(file.bytes);
  const indices = parseRanges(file.ranges, src.getPageCount());
  const copied  = await merged.copyPages(src, indices);
  copied.forEach(page => merged.addPage(page));
}
const bytes = await merged.save();

pdfjs-dist — Mozilla's PDF renderer, runs in browser. Used for generating page thumbnails:

const pdfjsLib = await import("pdfjs-dist");
pdfjsLib.GlobalWorkerOptions.workerSrc =
  `https://cdnjs.cloudflare.com/ajax/libs/pdf.js/${pdfjsLib.version}/pdf.worker.min.mjs`;

const pdf      = await pdfjsLib.getDocument({ data: new Uint8Array(bytes) }).promise;
const page     = await pdf.getPage(1);
const viewport = page.getViewport({ scale: 0.3 });
const canvas   = document.createElement("canvas");
canvas.width   = viewport.width;
canvas.height  = viewport.height;
await page.render({ canvasContext: canvas.getContext("2d"), viewport }).promise;
const thumb = canvas.toDataURL("image/jpeg", 0.7);

jszip — For packaging multiple split PDFs into a single ZIP download:

const JSZip = (await import("jszip")).default;
const zip   = new JSZip();

for (let i = 0; i < pageCount; i++) {
  const doc    = await PDFDocument.create();
  const [page] = await doc.copyPages(src, [i]);
  doc.addPage(page);
  const bytes  = await doc.save();
  zip.file(`page-${String(i + 1).padStart(3, "0")}.pdf`, bytes);
}

const zipBlob = await zip.generateAsync({ type: "blob" });

PDF Merger — page range selection

The interesting part of the merger is per-file page range selection. Users can specify "1-3,5,7-9" to select specific pages from each file before merging.

function parseRanges(input: string, pageCount: number): number[] {
  if (!input.trim()) return Array.from({ length: pageCount }, (_, i) => i);
  const pages = new Set<number>();
  const parts = input.split(",").map(s => s.trim());
  for (const part of parts) {
    if (part.includes("-")) {
      const [a, b] = part.split("-").map(Number);
      for (let i = a; i <= Math.min(b, pageCount); i++) pages.add(i - 1);
    } else {
      const n = parseInt(part, 10);
      if (n >= 1 && n <= pageCount) pages.add(n - 1);
    }
  }
  return [...pages].sort((a, b) => a - b);
}

With live validation and a page count display so users know exactly what will be included.

PDF Splitter — three modes

Rather than one split mode, I built three:

All pages individually — splits every page into a separate PDF, packages as ZIP. Simple, covers the most common use case.

Custom ranges — named ranges with labels. User creates entries like "Introduction: 1-3", "Chapter 1: 4-15", "Appendix: 16-20". Each becomes a separate PDF. Multiple ranges download as ZIP, single range downloads directly.

Visual page selection — click thumbnails to select specific pages, downloads as single extracted PDF. Most intuitive for non-technical users.

type SplitMode = "all" | "ranges" | "select";

PDF Canvas Builder — the contextual sidebar problem

The canvas builder uses Fabric.js. The interesting UX challenge was the property sidebar: showing all properties all the time creates visual noise and confuses users about what applies to what.

The solution was a contextual sidebar that shows only properties relevant to the selected object type:

Text selected → font, size, color, weight, style, alignment, line height, rotation
Shape selected → fill, stroke, stroke width, opacity, rotation, flip H/V
Image selected → opacity, brightness, contrast, saturation, grayscale, rotation, flip H/V
Nothing selected → hint card + add new object panels

type ObjType = "text" | "shape" | "image" | null;

function getObjType(obj: any): ObjType {
  const t = obj?.type?.toLowerCase() ?? "";
  if (["i-text","itext","text","textbox"].includes(t)) return "text";
  if (t === "image") return "image";
  if (obj) return "shape";
  return null;
}

The sidebar re-renders based on selObj.type, showing the right controls for whatever is selected. Image filters (brightness/contrast/saturation/grayscale) use Fabric's built-in filter pipeline.

The SSR problem with canvas-heavy components

Next.js SSR and Fabric.js don't mix. The solution is dynamic import with ssr: false:

// pages/tools/pdf-builder.tsx
const PdfBuilderClient = dynamic(
  () => import("@/components/pdf/PdfBuilderClient"),
  { ssr: false }
);

Same pattern for the merger/splitter — any component that touches window, document, or browser-only libraries needs this treatment in Next.js pages router.

Privacy by architecture

The key insight: when you don't build a server, you can't accidentally leak data to it. The privacy guarantee isn't a policy — it's an architectural constraint.

For PDF tools specifically this matters. Documents people merge and split often contain:

Contracts and NDAs
Financial statements
Medical records
Personal identification

None of those should be uploaded to a third party service just because someone needs to combine two PDFs.

Try them

PDF Merger — combine PDFs with page range selection
PDF Splitter — split by pages, ranges, or visual selection
PDF Canvas Builder — create PDFs from scratch

Open DevTools → Network tab while using any of them. No file upload requests. Everything stays in your browser.

If you're building browser-based file processing tools, the pdf-lib + pdfjs-dist combination covers most PDF use cases without any server infrastructure. Worth knowing about.