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

List blocked users

List the WhatsApp users blocked on this number. Cursor-paginated; pass nextCursor back as after to fetch the next page. The blocklist holds up to 64,000 users.

GET
/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

Query Parameters

accountId*string

WhatsApp account ID

limit?integer

Page size.

Range1 <= value <= 100
after?string

Cursor from a previous response's nextCursor.

Response Body

application/json

application/json

{  "blockedUsers": [    {      "waId": "string"    }  ],  "nextCursor": "string"}
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Check if a user is blocked

Definitive blocked-state lookup for a single contact. Meta exposes no membership endpoint, so this reads Zernio's blocklist mirror (kept in sync by the block/unblock endpoints; the first call per account backfills the mirror from Meta's full list). Constant-time regardless of blocklist size.

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.