DocTools Pro

The pitch is narrow and the pitch is honest: keep the file on the machine. DocTools Pro's entire value proposition is that the conversion runs in the browser's local memory rather than on a server, and the vendor leans on that hard — no uploads, no data in transit, no processing history, nothing stored, no analytics on your files. If that's the thing you actually care about, the alternative set is small and mostly paid. Strengths. Format coverage is genuinely broad for a free tool: the site lists 20 formats across three families and names them individually (PDF, DOCX, ODT, PPTX, EPUB, RTF, TXT, HTML; JPG, PNG, WebP, HEIC, SVG, BMP, TIFF, GIF; CSV, XLSX, ODS, XLS). The module split is sensible — converter, document studio, image engine, encryption — rather than one undifferentiated upload box. Batch handling is a real convenience: you can mix file types in a single drop and either apply one output setting across the batch or configure each file individually. Offline resilience is unusual and useful; the vendor says that once the page loads, the tools keep running if your connection drops, because there is no server in the loop. And Encrypt & Lock is broader than the document-only focus of most competitors: it password-protects documents, images, audio, video and archives, encrypting and decrypting in-browser. Weaknesses. Everything is bounded by your device. The vendor is upfront that performance depends on the hardware, that very large files may strain browser memory (even though there's no artificial size limit), and that OCR may be limited compared with desktop applications. Mobile works, but the site itself says larger files are easier on a desktop or laptop. There is also no collaboration layer at all — no shared workspaces, no version history, no cloud storage — and no e-signature. And there's no API or SDK, so anything you'd want to automate inside a pipeline is out of scope. Where it fits. Individuals and small teams who handle regulated or confidential material and want a zero-friction conversion step: a paralegal merging scanned exhibits, a freelancer scrubbing metadata-adjacent artefacts by keeping files local, a student splitting a textbook PDF, someone resizing iPhone HEIC photos for a web upload, or anyone who needs to add a password to a spreadsheet before emailing it. The free tier is the whole product — there's no upsell wall to hit and no seat maths to do. Where it doesn't. If you need AI-assisted editing, summarisation or generation, this isn't that tool. If your team needs a shared document workspace with history and permissions, you want a different category entirely. If you're a developer who needs to convert files programmatically at scale, the absence of an API is disqualifying. And if you need deep PDF authoring — form building, redaction, precise layout editing — a desktop suite will beat a browser tool every time.