One endpoint is the whole integration

Authentication

Create an API key in the dashboard under Integrations → API, and send it as a bearer token. Keys are scoped to one Organization and can be revoked at any time.

Authorization: Bearer wl_your_api_key

Keys are secrets — keep them server-side. Anything running in a browser should never hold one. (The Cancellation Capture snippet is different: it uses a separate publishable key that can only write captures, restricted to domains you allow.)

Send a cancellation

POST /api/v1/cancellations — the same pipeline a Stripe-detected cancellation enters: exit interview, AI follow-up, tagging, insights.

curl -X POST https://app.whyleft.com/api/v1/cancellations \
  -H "Authorization: Bearer wl_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "customer_email": "jane@example.com",
    "customer_name": "Jane Okonkwo",
    "plan_name": "Growth",
    "mrr_cents": 14900,
    "idempotency_key": "sub_1a2b3c-cancelled"
  }'

{
  "interview_id": "9f8e7d6c-...",
  "email_queued": true,
  "deduplicated": false
}

Fields

• customer_emailstringrequired

  Who cancelled. This is the address the exit interview is sent to.

• customer_namestringoptional

  Used to personalise the greeting. Never sent to the AI.

• plan_namestringoptional

  The plan they were on. Used for segmenting insights.

• mrr_centsintegeroptional

  Your customer's monthly revenue, in whole cents (14900 = $149). Drives lost-MRR and impact weighting.

• cancelled_atISO 8601optional

  Defaults to now. A future date schedules the interview instead of sending immediately.

• send_before_daysintegeroptional

  For a future cancellation, send the interview this many days before it (0 = on the day). Ignored for past dates.

• idempotency_keystringoptional

  Send the same key twice and you get the same interview back, with no second email. Use it if your webhook can retry.

• send_emailbooleanoptional

  Defaults to true. Set false to record the cancellation without interviewing — useful for backfilling history.

Response codes

• 201Created. The interview exists and the email is queued.
• 200Deduplicated — this idempotency_key was already used. No second email.
• 401Missing or invalid API key.
• 403No active subscription, or the account is pending deletion.
• 409Duplicate cancellation for this customer.
• 413Payload over 64 KB.
• 422Validation failed, or the recipient has unsubscribed. The response names the offending field.
• 429Rate limited. Respect the Retry-After header.

Retries and idempotency

Webhook deliveries retry. Pass an idempotency_key derived from something stable in your own system — a subscription id, an event id — and a repeated call returns the original interview with deduplicated: true instead of emailing the customer twice.

Requests are rate limited per key, and the body is capped at 64 KB. Every call is recorded in an audit log you can see in the dashboard.

Getting data out

Outbound webhooks fire on WhyLeft events, so you can push interviews and replies into Zapier, n8n, Make, or your own endpoint. Full exports are available from the dashboard, and a GDPR export endpoint returns everything held for a given customer.

Need something the API doesn't cover? Tell us — it's a short list and we'd rather it stayed short.