Zernio
Zernio
API Reference

WhatsApp

Templates

List templatesGETCreate templatePOSTGet templateGETUpdate templatePATCHDelete templateDELETEGet template by idGETUpdate template by idPATCHDelete template by idDELETELook up a library templateGET

Business Profile

Get business profileGETUpdate business profilePOSTUpload profile picturePOSTGet display name statusGETRequest display name changePOSTGet business usernameGETGet username suggestionsGETSet business usernamePOSTDelete business usernameDELETE

Groups

List active groupsGETCreate groupPOSTGet group infoGETUpdate group settingsPOSTDelete groupDELETEAdd participantsPOSTRemove participantsDELETECreate invite linkPOSTList join requestsGETApprove join requestsPOSTReject join requestsDELETE

Blocking

Check if a user is blockedGETList blocked usersGETBlock usersPOSTUnblock usersDELETE

Media

Download WhatsApp mediaGET

Conversions

Get CTWA conversions datasetGETProvision CTWA datasetPOSTList conversion eventsGETSend WhatsApp conversion eventPOST

Account Events

List account notificationsGET

Phone Numbers

Get number statusGETRegister a connected WhatsApp number on the Cloud APIPOSTMove a number to another profilePATCH

Calling

Get calling config for an accountGETEnable calling on a numberPOSTUpdate calling configPATCHDisable calling on a numberDELETECheck call permissionGETList call history for an accountGETInitiate outbound callPOSTGet a single callGETEstimate per-minute costGETGet calling config for a numberGETGet a call recordingGETStart caller-ID verification for a customer-brought numberPOSTConfirm the caller-ID verification codePOST

Flows

List flowsGETCreate flowPOSTGet flowGETUpdate flowPATCHDelete flowDELETEGet flow JSON assetGETUpload flow JSONPUTGet flow preview URLGETList flow versionsGETPublish flowPOSTDeprecate flowPOSTSend flow messagePOSTList flow responsesGETGet Flows encryption key statusGETRegister a Flows encryption keyPOST

Sandbox

List your sandbox sessionsGETStart a sandbox activationPOSTRevoke a sandbox sessionDELETE

Other

Request a Meta re-verification code for a BYO WhatsApp numberPOSTVerify the Meta re-verification code for a BYO WhatsApp numberPOST
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WhatsApp

Unblock users

Unblock one or more previously blocked WhatsApp users on this number. Up to 1,000 users per request; per-user failures are reported in failed without failing the rest of the batch.

DELETE
/v1/whatsapp/block-users

Authorization

bearerAuth
AuthorizationBearer <token>

API key authentication: send your Zernio API key in the Authorization header, prefixed with Bearer.

In: header

Request Body

application/json

TypeScript Definitions

Use the request body type in TypeScript.

Response Body

application/json

application/json

{  "unblocked": [    {      "input": "string",      "waId": "string"    }  ],  "failed": [    {      "input": "string",      "errors": [        "string"      ]    }  ]}
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Block users

Block one or more WhatsApp users on this number. Blocked users cannot message your number or see that you are online, and your sends to them return an error. Meta constraints, surfaced per-user in `failed` (the request itself still succeeds for the rest of the batch): - Only users who messaged your business within the last 24 hours can be blocked (failures outside the window report "Re-engagement required"). - Up to 1,000 users per request; the blocklist caps at 64,000. - Other WhatsApp Business accounts cannot be blocked.

Download WhatsApp media

Streams the binary for a WhatsApp attachment. This is the endpoint the `url` on a WhatsApp `attachments[]` entry points at, in both the `message.received` webhook and the List messages response. **This is an authenticated endpoint, not a public link.** Send `Authorization: Bearer <your API key>` exactly as you would for any other call. Passing the URL straight to a browser, an LLM vision API, or a no-code "download file" step without the header returns `401`. This is the most common integration mistake on this endpoint, and it differs from Instagram, Facebook and Telegram, whose `attachments[].url` is a direct CDN link that needs no header. **Fetch on receipt, not lazily.** WhatsApp media lives in Meta's media store, not ours, and it is removed after a limited retention window (currently 7 days, and Meta has been dropping some inbound media sooner). Once Meta drops it the media is unrecoverable and this endpoint answers `400` permanently, so retrying will never succeed. Download and store the bytes when the webhook arrives.

accountId*string

WhatsApp account ID

users*array<string>

Phone numbers (E.164) or WhatsApp user IDs to unblock.

Items1 <= items <= 1000