---
title: "Trial-enabled plan starts free window."
method: POST
path: "subscription.trial_started"
tags: ["subscription.* events"]
---

# Trial-enabled plan starts free window.

`POST subscription.trial_started` (webhook)

### When this fires

A subscriber starts a trial on a trial-enabled plan. Three paths emit it: a cardless trial, an access-code redemption against a trial plan, or a **Stripe** checkout that begins in a trial window.

Trial checkouts through the other providers (PayPal, Paystack, Razorpay, Skrill, CeyPay, CoinPayments) do not currently emit this event; only Stripe reports the trialing status transition back to Subscriby.

> Pairs with `member.trial_joined`: both fire together when a subscriber starts a trial on the cardless-trial and access-code paths.

The `data` keys differ by path. Absent keys are **omitted entirely**, not sent as `null`.

### Caveats

- On the cardless-trial and access-code paths this is paired with `subscription.created` and `member.trial_joined` for the same `subscription_id`. On the Stripe path it is paired with `subscription.activated` instead, and no `member.*` join event fires.
- Plans with `trial_days = 0` skip this event entirely.

### Related events

- `subscription.trial_converting`: fires 24h before `trial_ends_at`.
- `subscription.trial_expired`: fires if no conversion occurs.

## Headers

- `SB-Signature` string, required
- `SB-Event-Id` string, required
- `SB-Event-Name` string, required
- `Content-Type` string, required
- `User-Agent` string, required

## Payload

- object: The envelope every event is delivered in.
  - `id` string, required: A ULID unique to the event, prefixed `evt_`. Every retry carries the same id, so it is the key to deduplicate on.
  - `type` 'subscription.trial_started', required: The event name, always `subscription.trial_started` here.
  - `created_at` string, date-time, required: When the event was emitted, server time, ISO 8601.
  - `api_version` string, required: The contract version of the payload shape, `2026-05-01` today. A breaking change to a shape ships under a new version.
  - `project_id` string, uuid, nullable, required: The project the event belongs to; null for team-scoped and billing events.
  - `data` object, required: The event-specific payload. Keys that do not apply to a given emission are omitted rather than sent as null, so check for presence.
    - `subscription_id` string, uuid, required: Subscription identifier.
    - `plan_id` string, uuid, required: Plan the trial is on.
    - `subscriber_id` string, uuid, required: Subscriber's project-scoped user id.
    - `trial_ends_at` string, date-time, nullable, required: Present on every path. May be `null` on the Stripe path when the subscription row has no `trial_ends_at` recorded yet; fall back to [the subscription endpoint](https://docs.subscriby.net/api/v1/reference/subscriptions).
    - `access_code` string: Access-code path only. The full redeemed code.
    - `project_id` string, uuid: Access-code path only. Mirrors the envelope `project_id`.
    - `provider` string: Stripe path only. Always `stripe`.

## Acknowledgement `2XX`

Your endpoint acknowledged the delivery. Any 2xx status within 30 seconds marks it delivered; the response body is ignored.

## Other responses

- `default`: Any other status, a connection failure, or no answer within 30 seconds counts as a failed attempt. The delivery is retried 8 times, after 10 seconds, 30 seconds, 2 minutes, 10 minutes, 1 hour, 6 hours, 1 day, 3 days; the last failure dead-letters it, and it can be retried from the dashboard or `POST /v1/webhook-deliveries/{delivery}/retry`. After 20 consecutive failures the endpoint is paused until it is resumed.

---

[API](https://skmtc.dev/memberpass/apis/subscriby-rest-api.md) · [All operations](https://skmtc.dev/memberpass/apis/subscriby-rest-api/llms.txt) · [OpenAPI document](https://skmtc.dev/memberpass/apis/subscriby-rest-api/revisions/59c4df91d764?raw)