Changelog

What changed in the Gauge API, newest first. Additive changes, new endpoints, and anything you need to act on.

Breaking changes only ship behind a new Gauge-Version date and are announced here first, with a Deprecation and Sunset period.

21 October 2026: start WhatsApp Cloud conversations with a template

Additive, on API version 2026-10-21.

POST /v2/messages with to or contactId and an approved template now starts a WhatsApp Cloud conversation: Gauge creates or reuses the contact and the conversation and sends the template. The connection reports startConversations: true when templates are enabled. Start a conversation with a template.
Free text to someone on WhatsApp Cloud with no conversation answers 422 with reason outside_24h_window (it answered cannot_start_conversations before).
New 422 reasons, checked before anything is written: template_not_approved, template_language_not_found, template_variable_mismatch (previously a template that was not approved, or a missing variable, was refused without a reason; extra variables were ignored and are now refused).

Additive, on API version 2026-10-21.

New

Messaging: contacts (with upsert by channel identity, tags, merge and GDPR erasure), conversations (filters, status, assignment, team, topic, tags, notes, read), messages (text, templates, buttons and lists, files, quoted replies, metadata), media uploads, and templates.
POST /v2/messages answers 201 when sent during the request and 202 with status: queued when dispatched in the background; the Idempotency-Key also de-duplicates the send beyond 24 hours.
WhatsApp Web warm-up caps (429, whatsapp_web_minute_cap / whatsapp_web_daily_cap) and the whatsapp_web_unofficial warning on every send.
GET /v2/messages/{id}/attachments/{index}: a signed download of any file on a message.
503 media_unavailable on file uploads and downloads where a deployment has no public storage.
Message events: message.received, message.sent, message.status_updated (including sent for queued messages), conversation.created, conversation.updated, contact.created, contact.updated, delivered by the owner's visibility.
Webhooks from code: /v2/webhook-endpoints and the 30-day event log /v2/events, with redelivery (20 an hour per workspace, shared with the console).
The Gauge-Signature header (t=<ms>,v1=<hex>) and Gauge-Event-Id, Gauge-Event-Type, Gauge-Delivery-Attempt, Gauge-Webhook-Id on every delivery; the x-pulse-* headers stay.

Changed

An endpoint failing every delivery for 3 days is switched off and its owner told.
A delivery body is capped at 64 KB; a longer message is truncated with a fetchUrl.
Test keys and App-pinned keys are refused on the messaging routes.

The first dated version of /v2.

New

GET /v2/me: who a key is, its scopes, environment and rate-limit budget.
GET /v2/connections and GET /v2/connections/{id}: connected channels with their effective API capabilities, and a ban-risk warning on WhatsApp Web.
GET /v2/openapi.json: a generated OpenAPI 3.1 document with shared Error and Page schemas, an operationId and tags on every operation, and the webhook catalogue.
One error envelope and a closed list of error codes on /v1 and /v2.
X-Request-Id on every response, and bring your own UUID or ULID.
Idempotency keys, required on every /v2 POST.
Rate limits per key and per workspace, with RateLimit-* headers.
Scopes by area (messages:write, contacts:read, …), capped by the member's role when a key is created and when it is used.
Per-key IP allowlists, and a request log in Developers → Logs.

Changed

API access requires the Growth or Scale plan (402 plan_required otherwise).
A key stops working when its member leaves the workspace (401 key_owner_inactive).
/v1/conversations and /v1/contacts now respect the member's own and team visibility, as the console does.
Webhook * subscriptions receive the public catalogue only, and payloads carry only each event's documented fields.