Keep your form. Add the phone.
Most forms don’t need a rewrite. CrossUpload writes accepted file IDs into a hidden input of your choice, and your backend verifies them with a server-side API call before saving. In companion mode, your existing file input keeps working exactly as before.
The problem
- Rebuilding a working form just to add an upload feature is expensive and risky.
- Trusting IDs or URLs posted from hidden fields lets attackers attach someone else’s files.
How CrossUpload helps
Hidden JSON field
resultInput receives a JSON array of accepted file IDs and metadata; input and change events fire so your validation can react.
Server-side validation
Your backend calls GET /v1/files/{id} and checks the project, session and externalReference before attaching the file.
Companion mode
Add “Upload from your phone” next to an existing input. Local files still post as multipart; phone files arrive as IDs.
Never auto-submits
The visitor stays in control of your form.
Questions
What does my server receive?
A list of file IDs. Fetch metadata and temporary URLs from the API using your secret key.
Where teams use it
Ready to try it?
Free plan, no credit card. Talk to us at master@crossupload.com.
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