Is your logo really a vector file, or does it just look like one?

Drop it in above and you have the answer in about a second. If it is genuine vector artwork you are told so plainly. If it is a bitmap wearing a vector file extension, which is the common case, you are told that too, along with how much of the artwork is affected and a magnified view so you can see it for yourself rather than take a verdict on trust.

No software, no account and no upload. The check runs inside the browser you are reading this in.

The question that matters for print is not whether a file contains any vector elements. It is how much of the visible ink is resolution independent. A PDF holding one full page photograph plus a stray zero-size rectangle left behind by an export does contain a vector element, and a tool that counts elements will call it a vector file. It will still print exactly as badly as the photograph would.

So anything hidden, fully transparent, zero-sized or positioned outside the canvas is discarded first, and whatever is left is measured as a share of the artwork. That is why a file here can be reported as a bitmap in disguise even though it technically contains paths.

Almost always because the artwork was a bitmap and was printed larger than its pixels allow. A bitmap holds a fixed number of pixels, and printing it bigger does not create more of them, it spreads the ones there are over more paper. Vector artwork has no such ceiling, which is the entire reason printers ask for it.

If a file turns out to be a bitmap, the print size calculator works out the largest size it still holds up at, rather than leaving you to guess.

SVG has an image element, so a file can consist of a single base64 encoded PNG and nothing else and still be a completely valid SVG that opens correctly everywhere. It is the most common fake vector file there is, and it is usually made in good faith by someone who opened a logo image and saved it in a vector format.

You can catch it by hand: open the SVG in a text editor and look for a long run of characters after data:image/png;base64. The checker above reads the same thing, and also measures how much of the canvas that image covers.

SVG and SVGZ, PDF, AI in both its modern PDF form and the older PostScript one, EPS and DOS-EPS. Bitmaps are accepted rather than refused: drop in a PNG, JPEG, GIF, WebP, TIFF or BMP and you get its real pixel dimensions and what it can print at, which is more useful than being told the format is unsupported. CorelDRAW and Sketch files are recognised and named, then reported honestly as something a browser cannot inspect.

Several files at once is fine. Drop a folder's worth and page through the results.

There is no server to upload to. The file is read from your disk by your browser, examined in memory and forgotten. Open the network panel in your developer tools and drop a file in: you will see no requests at all, because the page makes none. It means you can check artwork you are not allowed to send to a third party, which rules out every checker that works by upload. How that is enforced.

A fuller reference on what each format can and cannot hold, the two traps peculiar to EPS, and how to tell what you have without any software at all is on the info page.