File uploads

SiteBackend can store files people attach to your forms: CVs, screenshots, briefs. Files are private: only members of your workspace can download them.

Turn on uploads for the form

Open Form → Settings → File uploads and switch on Accept file uploads. Until you do, file fields are ignored.

Add a file input and multipart encoding

A form that sends files must use enctype="multipart/form-data":

apply.html

<form action="https://api.sitebackend.com/forms/YOUR_FORM_ID" method="POST" enctype="multipart/form-data">
  <input type="email" name="email" required />
  <label>
    CV (PDF)
    <input type="file" name="cv" accept=".pdf" required />
  </label>
  <button type="submit">Apply</button>
</form>

Add multiple to an input to let people attach several files at once.

Check the inbox

Submitted files appear under Attachments on the submission, with a preview for images and a download button.

What are the limits?

	Free	Pro
Max size per file	10 MB	100 MB
Max size per submission (all files together)	25 MB	150 MB
Storage per workspace	500 MB	5 GB
Files per submission	10	10

You can set a lower size limit per form under Max file size. Photos attached to testimonials don't count toward your storage.

How do I restrict file types?

List the types you accept in Allowed file types, separated by commas. Use MIME types, wildcards or extensions:

image/*, application/pdf, .docx

Leave it empty to accept any type. Also set the input's accept attribute so the browser's file picker matches.

What happens when a file isn't accepted?

The whole submission is rejected and nothing is stored:

Status	`error`
`413`	`<file> is too large (max 10 MB per file)`
`415`	`<file>: this file type isn't accepted`
`400`	`Too many files (max 10 per submission)`
`413`	`This form's workspace is out of file storage`
`413`	`Submission is too large (max 25 MB)`

HTML forms show the error on the SiteBackend thank-you page; fetch requests get it as JSON.

How do I upload with JavaScript?

Send a FormData object; the browser sets the multipart encoding for you. Don't set Content-Type yourself.

const res = await fetch(form.action, {
  method: "POST",
  body: new FormData(form), // includes <input type="file"> fields
  headers: { Accept: "application/json" },
});

Where do the files show up?

Inbox: under Attachments on each submission.
Notifications: each file's name, size and a link to download it (login required).
CSV export: one column per file field, with download links.

Deleting a submission, form, site or workspace also deletes its files. Spam submissions never store files.