API reference: POST /api/feedback

Create one feedback item. This is the same endpoint the widget uses, and it is open to direct calls from any language.

POST https://usero.io/api/feedback
Content-Type: application/json

• CORS: Access-Control-Allow-Origin: *. Call it straight from browsers, mobile apps, desktop apps, or servers.
• Auth: the clientId in the body identifies your project. No API key, no auth header.
• Abuse control: if your client has a domain allowlist configured in Settings, requests from other origins get a 403. New clients have no allowlist, so everything is accepted.

clientId is always required. rating and comment are each optional, but every submission must include at least one of them: a rating (1 to 4), a non-empty comment, or both. Everything else is optional.

Field	Type	Required	Description
clientId	string	yes	Your project id, starts with client_. See Find your clientId.
rating	integer	one of rating / comment	1 to 4: 1 Terrible, 2 Bad, 3 Good, 4 Amazing.
comment	string	one of rating / comment	Free-text feedback. Must be non-empty if no rating is sent.
userEmail	string	no	The submitter's email, must be a valid address. Lets you reply and groups feedback by person in the dashboard. An empty string is treated as absent.
pageUrl	string	no	URL the feedback was given on. If omitted, the server falls back to the Referer header.
pageTitle	string	no	Title of the page the feedback was given on.
referrer	string	no	The page the user arrived from.
environment	string	no	Optional. Omit it unless you separate environments like production and staging; feedback without it lands in your default inbox.
screenshots	array	no	Screenshot objects returned by POST /api/screenshots. Each item: fileName (string), url (string), fileSize (number), mimeType (string), width (number, optional), height (number, optional).
metadata	object	no	Arbitrary JSON attached to the feedback, 10KB max when serialized. Good place for app version, OS, build number, or feature flags.
sessionReplayId	string	no	1 to 128 characters. Links the feedback to a session replay recorded by @usero/sdk session replay.
replayOffsetMs	integer	no	Non-negative millisecond offset into the linked replay at which the feedback was given.

Minimal submission:

curl -X POST https://usero.io/api/feedback \
  -H "Content-Type: application/json" \
  -d '{"clientId": "YOUR_CLIENT_ID", "rating": 3}'

Full-field submission:

curl -X POST https://usero.io/api/feedback \
  -H "Content-Type: application/json" \
  -d '{
    "clientId": "YOUR_CLIENT_ID",
    "rating": 2,
    "comment": "Export to CSV times out on large projects",
    "userEmail": "jamie@example.com",
    "pageUrl": "https://yourapp.com/projects/42/export",
    "pageTitle": "Export project",
    "referrer": "https://yourapp.com/projects/42",
    "environment": "staging",
    "metadata": {
      "appVersion": "2.4.1",
      "os": "macOS 15.2",
      "build": 1842
    }
  }'

For native apps, metadata is the place for app version, OS version, and build number, so every report arrives with the context you need to reproduce it.

Success:

{ "success": true, "feedbackId": "abc123" }

Status	Body	Meaning and fix
400	{"error": "Invalid data provided", "issues": {"rating": ["..."]}}	Validation failed. issues names each failing field. The most common cause: neither rating nor a non-empty comment was sent.
400	{"error": "Metadata too large (max 10KB)"}	Serialized metadata exceeds 10KB. Trim it.
403	{"error": "Domain not allowed"}	Your client has a domain allowlist and this request's origin is not on it. Add the origin in Settings, or clear the allowlist.
500	{"error": "Internal server error"}	Something broke on our side. Safe to retry.

• Screenshot uploads: two-step flow to attach images
• Session replay: where sessionReplayId comes from
• Find your clientId