Webhooks

Get an HTTP callback whenever a respondent finishes a survey, with the full set of answers — no need to call back into the API to fetch the response.

Creating an endpoint

From your project’s Integration page, add a webhook endpoint with a URL (HTTPS only — loopback and private IPs are rejected) and the events it should receive. Your project’s secret key (sk_...) is used as the signing secret — one is created automatically on a plan with Integrations enabled if you don’t already have one — see Server API → Webhook signing with your secret key. On a plan without Integrations, a whsec_... secret is generated instead. Either way, the secret is never returned by create/list/update — use Reveal signing secret when you need it.

Via the API:

POST /api/v1/projects/{projectId}/webhooks
Content-Type: application/json
Authorization: Bearer {token}
 
{
  "url": "https://api.acme.com/hooks/1sygnal",
  "events": ["survey.response.created"]
}

Event catalog

Endpoints reject unknown event names on create/update (400) — including any name not in this table, so a typo or a stale integration can’t silently subscribe to nothing.

wasDirectTarget

survey.response.created and survey.dismissed payloads both carry wasDirectTarget, reporting whether the respondent was ever a direct target of the survey via the API’s targeting endpoint. Two things a consumer can’t infer from the field name:

• Historical, not current. It reflects whether a target row has ever existed for this user and survey — an expired target still reads true.
• Additive, not exclusive. Targeting only adds recipients on top of whatever a survey’s trigger rules already deliver to. false is the normal value for most respondents in the default automatic trigger mode, since trigger rules deliver to untargeted users too. Only api_only surveys are target-exclusive — there, wasDirectTarget is effectively always true.

Envelope and headers

Every delivery is a POST with this envelope:

{
  "id": "019887c1-5a03-7d44-8b91-2c3d4e5f6a7b",
  "event": "survey.response.created",
  "timestamp": "2026-08-15T09:41:07.004Z",
  "payload": { "...": "..." }
}

Every timestamp across the API — timestamp here, and every *At field in a payload — is millisecond-precision ISO 8601, always UTC: 2006-01-02T15:04:05.000Z. Parse it with any standard ISO 8601 parser; don’t assume a fixed string length.

Verifying the signature

The signature is computed over the exact bytes sent — verify against the raw body, not a re-serialized copy of the parsed JSON (key ordering, whitespace, and number formatting can all change the bytes without changing the meaning).

Node.js

import { createHmac, timingSafeEqual } from "node:crypto";
 
function verify(rawBody, signatureHeader, signingSecret) {
  const expected = "sha256=" + createHmac("sha256", signingSecret).update(rawBody).digest("hex");
  const a = Buffer.from(signatureHeader);
  const b = Buffer.from(expected);
  return a.length === b.length && timingSafeEqual(a, b);
}

Go

func verify(rawBody []byte, signatureHeader, signingSecret string) bool {
	mac := hmac.New(sha256.New, []byte(signingSecret))
	mac.Write(rawBody)
	expected := "sha256=" + hex.EncodeToString(mac.Sum(nil))
	return hmac.Equal([]byte(signatureHeader), []byte(expected))
}

Python

import hmac, hashlib
 
def verify(raw_body: bytes, signature_header: str, signing_secret: str) -> bool:
    expected = "sha256=" + hmac.new(signing_secret.encode(), raw_body, hashlib.sha256).hexdigest()
    return hmac.compare_digest(signature_header, expected)

Delivery semantics

Delivery is at-least-once — a receiver that processes a request and then fails to respond (timeout, crash, network blip) will get it again. Dedupe on X-1Sygnal-Delivery-Id, which is stable across retries of the same delivery.

Deliveries to one endpoint can arrive out of order. Order by payload.submittedAt, not arrival order.

Retries: up to 6 attempts per delivery, isolated per endpoint (a failure on one endpoint never delays or blocks delivery to another). 5xx responses and transport errors (timeouts, DNS failures, connection resets) are retried; any 4xx response is treated as final and not retried. Your endpoint should acknowledge fast and process off the request — the client timeout is 10 seconds.

Localization

surveyName, questionText, and valueLabels arrive in the language the respondent actually saw — the survey render, not a guess. languageCode on the payload names that language.

Key on questionId and value, which are stable identifiers — never on display text, which is meant to be shown to a human, not parsed. A survey with only some questions translated to a given language mixes languages within one payload: each string falls back to the survey’s base language independently, question by question.

Data protection

This payload egresses respondent free text and EMAIL_INPUT answers to a customer-controlled URL over the public internet — that’s a meaningfully bigger surface than the IDs-only shape it replaced. Endpoints should be HTTPS (enforced on create), and access-controlled on your side — anyone who can read requests to that URL can read what your respondents wrote. See Privacy & Consent for how consent and data minimization apply to survey responses generally.

Value shapes by question type

valueLabels resolves option IDs to their displayed text for every choice-bearing type above (including matrix types) — absent for scalar/text types, since the value is already human-readable there.

Only answered questions appear in answers — a skipped optional question is simply absent, so consumers must tolerate gaps rather than assuming every survey question shows up.

Reference delivery

POST /hooks/1sygnal HTTP/1.1
Host: api.acme.com
Content-Type: application/json
X-1Sygnal-Event: survey.response.created
X-1Sygnal-Delivery-Id: 019887c1-5a03-7d44-8b91-2c3d4e5f6a7b
X-1Sygnal-Signature: sha256=3b9f0a1c7e5d84f2a06b1d93c8e47f5a2d1b6c09e8f37a45b2c1d0e9f8a7b6c5

{
  "id": "019887c1-5a03-7d44-8b91-2c3d4e5f6a7b",
  "event": "survey.response.created",
  "timestamp": "2026-08-15T09:41:07.004Z",
  "payload": {
    "responseId": "019887c1-4f2a-7c31-9e08-1a2b3c4d5e6f",
    "surveyId": "019870aa-3b11-7d90-8c44-5f6e7d8c9b0a",
    "surveyName": "Post-checkout feedback",
    "projectId": "01984f22-8c07-7b12-a3d5-9e0f1a2b3c4d",
    "externalUserId": "user_84213",
    "anonymousId": "anon_7f3c9d2e18b64a05",
    "userProfileId": "019885d0-1e44-7a88-b012-3c4d5e6f7a8b",
    "languageCode": "en",
    "startedAt": "2026-08-15T09:40:12.480Z",
    "submittedAt": "2026-08-15T09:41:06.912Z",
    "clientContext": {
      "locale": "en-GB",
      "platform": "web",
      "os": "macOS",
      "sdkVersion": "1.4.2"
    },
    "answers": [
      {
        "questionId": "019870aa-3b11-7d90-8c44-5f6e7d8c9b11",
        "questionType": "NPS",
        "questionText": "How likely are you to recommend us to a friend?",
        "order": 0,
        "value": 9
      },
      {
        "questionId": "019870aa-3b11-7d90-8c44-5f6e7d8c9b12",
        "questionType": "MULTIPLE_CHOICE_SINGLE",
        "questionText": "What did you come here to do today?",
        "order": 1,
        "value": "019870aa-3b11-7d90-8c44-5f6e7d8c9c01",
        "valueLabels": ["Complete a purchase"]
      },
      {
        "questionId": "019870aa-3b11-7d90-8c44-5f6e7d8c9b13",
        "questionType": "MULTIPLE_CHOICE_MULTI",
        "questionText": "Which parts of checkout felt slow?",
        "order": 2,
        "value": [
          "019870aa-3b11-7d90-8c44-5f6e7d8c9c11",
          "019870aa-3b11-7d90-8c44-5f6e7d8c9c13"
        ],
        "valueLabels": ["Address entry", "Payment confirmation"]
      },
      {
        "questionId": "019870aa-3b11-7d90-8c44-5f6e7d8c9b14",
        "questionType": "TEXT_LONG",
        "questionText": "Anything else you'd like us to know?",
        "order": 3,
        "value": "Card form kept resetting when I switched tabs."
      }
    ],
    "wasDirectTarget": false
  }
}

The same response from a respondent whose device reported fr-FR, on a survey with supportedLanguages: ["en","fr"], differs only in the localized strings:

{
  "languageCode": "fr",
  "surveyName": "Retour après commande",
  "answers": [
    {
      "questionId": "019870aa-3b11-7d90-8c44-5f6e7d8c9b12",
      "questionType": "MULTIPLE_CHOICE_SINGLE",
      "questionText": "Que veniez-vous faire aujourd'hui ?",
      "order": 1,
      "value": "019870aa-3b11-7d90-8c44-5f6e7d8c9c01",
      "valueLabels": ["Finaliser un achat"]
    }
  ]
}

survey.dismissed sample

Fires when a respondent closes a survey without completing it:

POST /hooks/1sygnal HTTP/1.1
Host: api.acme.com
Content-Type: application/json
X-1Sygnal-Event: survey.dismissed
X-1Sygnal-Delivery-Id: 019887c2-6b14-7e55-9c02-3d4e5f6a7b8c
X-1Sygnal-Signature: sha256=4c0a1b2d8f6e95a3b17c2ea4d9f58a3b2e1c7d0af9048b56c3d2e1f0a9b8c7d6

{
  "id": "019887c2-6b14-7e55-9c02-3d4e5f6a7b8c",
  "event": "survey.dismissed",
  "timestamp": "2026-08-15T09:45:22.310Z",
  "payload": {
    "surveyId": "019870aa-3b11-7d90-8c44-5f6e7d8c9b0a",
    "projectId": "01984f22-8c07-7b12-a3d5-9e0f1a2b3c4d",
    "userProfileId": "019885d0-1e44-7a88-b012-3c4d5e6f7a8b",
    "externalUserId": "user_84213",
    "dismissedAt": "2026-08-15T09:45:22.310Z",
    "wasDirectTarget": false
  }
}

externalUserId and anonymousId are each omitted entirely (not sent as "") when not applicable — an anonymous respondent carries anonymousId but no externalUserId, and vice versa for an identified one.

Delivery log

GET /api/v1/projects/{projectId}/webhooks/{webhookId}/deliveries returns the delivery history, paginated:

{
  "data": [
    {
      "id": "...",
      "webhookEndpointId": "...",
      "eventType": "survey.response.created",
      "statusCode": 200,
      "responseTimeMs": 143,
      "retryCount": 0,
      "errorMessage": null,
      "deliveredAt": "2026-08-15T09:41:07.100Z"
    }
  ],
  "hasMore": false
}

Deliveries older than 30 days are pruned automatically. Payloads over 16KB are stored truncated in the log (the full body is still sent on the wire — only the audit copy is capped).