API Reference

/forms/{formId}/fields/{fieldId}/upload-urls

post
https://www.formstack.com/api/v2025/forms//fields//upload-urls

Generate presigned S3 upload URLs for a file field. Upload each file directly to its returned uploadUrl with an HTTP PUT (bypassing the request-body size limit), then submit the matching fileKey as the field's subvalue when creating the submission. Presigned URLs expire after 2 hours.

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Path Params
integer
required

The unique identifier of the form

integer
required

The file field to upload to

Body Params

Request body for generating presigned S3 upload URLs for a file field.

filenames
array of strings
length between 1 and 20

Original filenames to generate upload targets for. One presigned URL is returned per filename.

filenames
Responses

400

Invalid request: filenames missing/empty, more than the per-field file limit, or the field is not a file field

403

Forbidden

404

Form or field not found

Updated about 1 month ago

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application/json

Updated about 1 month ago