Choosing the right conversion tool for your task

Start with the file type you have, not the outcome you want.

FormatOS is built around an upload-first approach: you upload your file, and the workspace shows the actions that genuinely apply to it. This reduces the chance of choosing a tool that is mismatched to the file, and it catches the common case where a file is not what its extension says it is.

If you already know exactly what you need, the full tool directory lists every active tool by category. If you do not, dropping the file on the homepage is faster than reading a list.

For PDF work, the choice between tools depends on what you are changing:

• Page structure: split, merge, reorder, rotate, extract pages, delete pages
• Page content: add page numbers, add a watermark
• File properties: compress, remove metadata

Each of these is a distinct operation. Doing them all in sequence requires multiple passes, and the order matters: add page numbers after reordering, not before, or the numbering will follow the old sequence.

For images, the distinction between format conversion, quality adjustments and metadata handling matters:

• Format: JPG to PNG, PNG to WebP, HEIC to JPG, SVG to PNG
• Quality and dimensions: compress, resize, crop
• Metadata: remove EXIF data

You can chain these (for example, resize first, then convert format, then compress) but the order affects the final quality. As a rule: crop, then resize, then convert, then compress. Each step after compression re-encodes an already-degraded image.

For structured data, the question is which format the receiving system expects. CSV to JSON and JSON to CSV cover the common pair; XML and YAML conversions are available for configuration and API work. Where data is messy before conversion, the CSV cleaner is the step people skip and then regret.

For text, the tools are single-purpose by design: word counting, case conversion, encoding, cleanup. Pick the one that names what you want to do.

For sending files to other people, the key question is usually format compatibility and file size.

Convert to a format the recipient can open without special software, usually PDF for documents, JPEG or PNG for images, and compress if the file exceeds your email provider's attachment limit. A ZIP archive handles multiple files cleanly, and there are purpose-built variants for email, form uploads and client delivery.

Best formats for email attachments covers the limits in detail.

A common request: twelve photographs from a phone need to go to someone as a single attachment, and the recipient is on a work machine with a 10 MB limit.

The wrong order is to zip them first. The photos are HEIC, so half the recipients cannot open them; they are also full-resolution, so the ZIP is large and, because JPEG and HEIC are already compressed, zipping barely shrinks it. You end up with one large archive full of files that will not open.

The order that works runs the cheapest, most destructive-to-undo steps last:

1. HEIC to JPG first, so the files open everywhere. Doing this before resizing means one conversion rather than twelve decisions later.
2. Resize to the largest size the recipient will actually look at. This is the step that does most of the work; a phone photo is often four times wider than anyone needs.
3. Compress once, at a moderate quality, and check one image at full size before doing the rest.
4. Package into a ZIP for email last, as a container rather than a compressor.

The general rule behind that sequence: convert format before changing dimensions, change dimensions before compressing, and archive last. Each step after compression re-encodes an image that has already lost detail, so anything that shrinks the pixel count belongs before the compressor, not after it.

Sometimes the answer is that FormatOS is not the right place. It does not process video or audio, does not remove DRM or copy protection, does not recover passwords, and does not download media from other websites. These are deliberate exclusions, documented on the tool limitations page rather than discovered halfway through a task.

If what you need is on that list, a different tool is required, and knowing that in thirty seconds is more useful than a tool that appears to work and produces a bad result.