Best Free File Converters in 2026: Privacy, Speed & Format Support Compared

Updated June 2026 · 6 min read

I keep a folder of test files — a HEIC photo, a WebP screenshot, a 20-page PDF, a JSON export with 5000 rows. Every time I find a new converter, I throw these files at it and time the results. Most converters fail at least one format. Some upload everything to a server without making it obvious. Here's what I've found after testing the top contenders.

What to Look For in a Converter

Before we get to the list, here's what matters:

• Privacy (does it upload your files?): The most important criterion. If a converter uploads your files to a server, that server now has a copy. Look for "browser-based" or "client-side" converters.
• Format support: How many input/output formats are supported? Can it handle modern formats like HEIC, WebP, AVIF?
• Batch processing: Can you convert multiple files at once? Is there a file count limit?
• Speed: Browser-based converters are instant (no upload time). Server-based ones depend on your connection and the server's queue.
• File size limits: Many tools cap files at 10MB, 25MB, or 100MB. The best have no limits beyond your device's memory.

Top Free File Converters in 2026

1. Formly — Best Overall (Browser-Based)

Privacy: 100% local — no upload, no server. Formats: HEIC, WebP, PNG, JPG, SVG, PDF, JSON, CSV. Batch: Yes, unlimited files. Limits: 50MB per file (browser memory). Best for: Privacy-conscious users who need multiple format conversions in one tool.

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2. CloudConvert — Best for Enterprise Formats

Privacy: Server-based (files uploaded). Formats: 200+ formats including CAD, eBook, vector. Batch: Yes (25 files/day free). Limits: 25 conversions per day on free plan. Best for: Business users needing obscure format support (e.g., DWG to PDF).

3. Zamzar — Easiest to Use

Privacy: Server-based (files deleted after 24 hours). Formats: 100+ formats. Batch: Yes (2 files free). Limits: 50MB/file, 2 files/day free. Best for: Quick one-off conversions with minimal friction.

4. Convertio — Best Chrome Extension

Privacy: Server-based. Formats: 300+ formats. Batch: Yes (10 files free). Limits: 100MB/file, 10 conversions/day free. Best for: Chrome users who convert files from Google Drive or Dropbox.

Privacy Comparison at a Glance

Our Recommendation

For most people, a browser-based converter like Formly is the best choice — it's faster (no upload/download), truly private, and has no daily limits. Server-based tools like CloudConvert or Zamzar are better when you need obscure professional formats (CAD, eBook, pre-press) that browsers can't handle natively.

Whatever you choose, always check where your files are going. A "free" converter that uploads your data may not be free at all.

Written by Sam Taylor — Full-Stack Developer. building web tools for years. Built Formly to replace 15 bookmarked converter sites with one URL. More about me →