subscription.* events

Trial-enabled plan starts free window.

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.
postWebhooksubscription.trial_started

Headers

SB-Signaturestring required

t=<unix seconds>,v1=<hex>: the HMAC-SHA256 of "<t>.<raw body>" under the endpoint's secret. Verify it before acting, and refuse a t more than 300 seconds from now. During a secret rotation a v0= signature under the previous secret may precede v1=.

SB-Event-Idstring required

The event's ULID, bare. The envelope's id is the same ULID prefixed evt_, so strip the prefix before comparing. Deduplicate on it: a retry carries the same id.

SB-Event-Namestring required

The event name, the same as the envelope's type.

Content-Typestring required

Always application/json.

User-Agentstring required

Always Subscriby-Webhooks/1.0.

Payload

idstring 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_atstring date-time required

When the event was emitted, server time, ISO 8601.

api_versionstring required

The contract version of the payload shape, 2026-05-01 today. A breaking change to a shape ships under a new version.

project_idstring uuid nullable required

The project the event belongs to; null for team-scoped and billing events.

Response

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

Changes

Webhooks have no change history: a webhook is keyed by its event name rather than a path and method, so no recorded change can name it.