Omnisend

Omnisend Contacts API

The Contacts API from Omnisend — 7 operation(s) for contacts. Version 2026-03-15, harvested from Omnisend's published contract.

Documentation GitHub OpenAPI

Business capability

Customer Data Management BC-420.10

Operations 7

Each operation below carries the questions people ask an LLM about it and the instructions they give an agent to run it. Generated by API Evangelist overlay

GET /contacts List contacts · List contacts #

Ask an LLM

“Which contacts carry a specific tag?”

“Can I look up contacts by phone number?”

Tell an agent

List contacts tagged {tag}.

Find contacts with email {email}.

PATCH /contacts Update a contact by email address · Update contact by email #

Ask an LLM

“Can I update a contact using only their email address?”

“What fields can I change on a contact when all I know is their email?”

Tell an agent

Update the contact with email {email} to first name {firstName}.

Change the city of the contact whose email is {email} to {city}.

POST /contacts Create or upsert a contact · Create or update existing contact #

Ask an LLM

“How do I add a new subscriber, or update them if the email already exists?”

“Can I set custom properties and tags when creating a contact?”

Tell an agent

Create a contact with identifiers {identifiers}, first name {firstName} and last name {lastName}.

Add a new contact with identifiers {identifiers} and tags {tags}.

GET /contacts/{id} Get one contact by ID · Get contact #

Ask an LLM

“Can I fetch one contact's full profile by its contact ID?”

“What details are stored on the contact record with a given ID?”

Tell an agent

Show contact {id}.

Get the profile of the contact with ID {id}.

PATCH /contacts/{id} Update a contact by ID · Update contact by ID #

Ask an LLM

“How do I update a contact's details when I have their contact ID?”

“Can I change a contact's birthdate or gender by contact ID?”

Tell an agent

Update contact {id} with last name {lastName}.

Set custom properties {customProperties} on contact {id}.

DELETE /contacts/tags Remove tags from many contacts · Batch remove tags #

Ask an LLM

“Can I remove a tag from many contacts in one call?”

“How can I strip tags from all members of a segment?”

Tell an agent destructive · confirm first

Remove tags {tags} from contacts {contactIDs}.

Take tags {tags} off every contact in segment {segmentID}.

POST /contacts/tags Add tags to many contacts · Batch add tags #

Ask an LLM

“Can I add a tag to every contact in a segment at once?”

“Is there a way to bulk tag a list of email addresses or phone numbers?”

Tell an agent

Add tags {tags} to the contacts with emails {emails}.

Tag everyone in segment {segmentID} with {tags}.

Omnisend Contacts API

Operations 7

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