About Toolium

Why Toolium exists

Most free online tools have the same shape: you upload your file, a server processes it, you get a download link, and somewhere along the way an ad network or analytics provider learns more about you than you realize. For tasks like merging two PDFs or compressing a screenshot, that trade-off feels backward. The processing is simple enough to happen on your own machine; the only reason it usually does not is that running JavaScript in a browser was historically too slow for things like PDF parsing or image compression.

That changed a few years ago. Browsers now ship Web Workers and high-performance JavaScript engines that can do real work locally. Libraries like pdf-lib, pdf.js, and browser-image-compression let you process files entirely client-side, at speeds comparable to server-based alternatives. Toolium is built on that foundation. Every tool runs in your browser tab. Nothing gets uploaded.

Who built this

Toolium is an independent project, built and maintained by a single developer. There is no team, no investors, no roadmap pressure from stakeholders. That means choices about what to build and how to build it come from one place: what tools were missing or annoying to use elsewhere.

The project started in June 2026 with a single tool (PDF Merge, the most broken category at the time) and grew tool by tool as new needs came up. Each tool ships only when it works correctly for the edge cases I can think of and test: oddly-encoded PDFs, transparent PNGs being converted to JPG, CSVs with semicolon delimiters, JWT tokens with non-ASCII characters, regex patterns prone to catastrophic backtracking. Those are the cases that break most free tools quietly; I fix them and document them in the per-tool guides.

What I've learned shipping 34 tools

Building a wide tool suite has taught me a few things that show up in every page:

• Privacy is a real feature.Server-side processing is often promoted as "more powerful," but for the tasks people need (PDF merging, image compression, format conversion), the browser is plenty fast and the privacy benefit is enormous. A confidential document never gets uploaded.
• Edge cases matter more than core features.The difference between a tool you trust and one you do not is whether it handles the weird cases: a PDF with form fields, a JPEG with EXIF rotation metadata, a CSV with embedded newlines in a quoted field. My per-tool guides explain what I handle and what I don't.
• Honest limitations beat false promises. Several tools have file size limits because of browser memory constraints. Some tools (image upscaling, PDF OCR) I have not built because the browser-side libraries are not yet good enough. I say so on the page rather than letting you find out after a crash.

How I keep tools accurate

Every tool gets a few rounds of edge-case testing before it ships. I maintain a list of known issues per tool and fix them in priority order. A few examples of bugs I shipped fixes for in the past year:

• Markdown Preview was vulnerable to XSS via embedded HTML; fixed by adding DOMPurify sanitization.
• Regex Tester could freeze the tab on catastrophic backtracking patterns; fixed by moving execution to a Web Worker with a 1-second timeout.
• Image Format Converter would produce a black background when converting transparent PNGs to JPG; fixed by compositing onto white before encoding.
• JWT Decoder mishandled UTF-8 in claims; fixed by routing decode through TextDecoder.
• Word Counter undercounted sentences with abbreviations and CJK text; fixed by using Intl.Segmenter where available.

I update the per-tool guides when behavior changes so the documentation stays in sync with the code.

Every tool page includes a guide explaining what the tool does, common pitfalls, and answers to questions people ask. The guides are written from how each tool behaves in code, not a generic template. When I change a tool's behavior, I update the guide. When I learn about a real edge case from a user, I add it to the FAQ.

If a guide and its tool ever disagree, treat the tool as right and the guide as the bug. The contact info below reaches the person who can fix it.