Special inputs

File upload (fileUpload)

Lets users attach files. Save files as decides where the file goes:

• Base64 in the form data (the default): nothing is sent anywhere. The file is read in the browser and its content travels inside the form value, so whoever receives the submitted form gets the file too.
• Upload to server (data source): each file is sent to the Upload data source as soon as it is picked, and the form value keeps only the key your server returns.

The value looks the same either way (an array of these when Multiple is on), which keeps the backend simple:

{ "name": "cv.pdf", "size": 48213, "type": "application/pdf", "lastModified": 1790764181739, "contentType": "application/pdf", "base64": "JVBERi0xLjcK..." }

With Upload to server, fileKey takes the place of base64.

Property	What it does
Save files as	Base64 in the form data or Upload to server (data source). The fields below marked server only show in the second mode.
Accepted types	Restrict extensions/MIME types per HTML accept rules (e.g. .pdf,image/*)
Max files	How many files may be attached; further uploads are blocked at the limit
Max file size (MB)	Oversized files are rejected before upload
Dropzone text	Caption of the drag-and-drop area. Keep it short and say what to do
Upload data source (server)	Source that receives the file: a POST (or configured method) with FormData
Upload form field name (server)	The FormData field name for the file (e.g. file)
Download data source / Delete data source (server)	Sources for fetching and removing stored files; the file key is passed via the key field below
File key / name / size / type field (server)	Field names in the server's response (default: key, name, size, contentType)

Set a max file size with base64

Base64 makes the value about a third larger than the file itself, and the whole value travels with every submit. Keep Max file size sensible (a few MB) or switch to Upload to server for large files.

A few things worth knowing before you brief your developer:

• In server mode uploads are always sent as multipart/form-data with a single field (its name is Upload form field name), never JSON. Any Request body template configured on the upload source is ignored; only {placeholders} in its URL are used.
• With Max files > 1, files upload as separate sequential requests, not one batch call.
• There's no upload progress percentage, only pending/ready/error per file, and no resumable or chunked upload.
• A view saved before Save files as existed keeps uploading if it has an upload data source.

For the exact request/response JSON your backend must implement, see File upload requests in the developer docs.

Typical setup, CV upload:

• Name: cvFile, Accepted types: .pdf, Max size: 5 MB, Required: on.
• Save files as: Upload to server, upload data source uploadDocument (a REST source configured by your developer). For a small form that is emailed as a whole, Base64 in the form data needs no backend setup at all.

Check with expressions:

visibleIf on "Continue" hint:  isEmpty({cvFile})
len({attachments}) > 0         → at least one file attached

Signature pad (signaturePad)

A draw area for a handwritten signature (mouse or touch). The value is the signature image data, stored under the element's name and submitted with the form.

Property	What it does
Pen / background color	Drawing style
Clear button	Lets the user retry
Required	Signature must be present before submit

Use it at the end of agreements together with a Single checkbox ("I confirm the data is correct").