Selzy API + MCP (2026): no official MCP server, flat REST

Selzy exposes one flat, unversioned REST API at https://api.selzy.com/en/api/{method}, authenticated by an api_key parameter and nothing else, no OAuth, no bearer token, no version segment. There is no official SDK in any language, and as of August 2026 no official Selzy MCP server: the only turnkey agent path is Zapier MCP, which reaches four operations. The compensating fact is that the API is simple enough, form-encoded in, JSON out, one credential, that a self-hosted MCP wrapper is small work.

At a glance

MCP integration in 2026

MCP is how an agent gets typed, permissioned access to a SaaS product instead of a raw HTTP client and a key. For Selzy, no such server exists from the vendor and the community has not filled the gap, so the question becomes how cheaply you can build the bridge yourself.

Available MCP servers

Three entries matter when wiring an agent to Selzy. Only one is an actual MCP server, and it is not Selzy’s.

Selzy API essentials

Everything runs through one host and one URL shape: /{lang}/api/{method}, where lang is en, ua or ru and sets the language of error messages, not campaign content. Methods are verbs, not resources, you call sendEmail, never POST /campaigns.

Two consequences follow. There is no deprecation window to watch: method-level changes ship in place, so your own contract tests are the only early-warning system. And because the language code occupies the version slot, tutorials hardcoding /ru/api/ still work, they just return Russian error strings, maddening to debug in a log aggregator. Pin en.

Event notification system (setHook)

Events cover email_status (sent, delivered, rejected, read, link clicked), subscribe, subscribe_primary, unsubscribe, campaign_status, email_check, user_payment and user_info. The body carries auth (an MD5 hash), num (a sequence number) and events_by_user, an array of login, event_name, event_time and event_data objects. The retry policy is the part to design around, see the gotchas.

Authentication methods

Selzy has one authentication mechanism plus one mandatory extra parameter that catches integration builders. No OAuth 2.0 flow, no bearer header, no scoped tokens, a Selzy API key is an account-wide credential.

API key parameter

Every request carries api_key as a query-string or form parameter. Because it travels as a parameter rather than a header, GET writes it into every proxy, CDN and access log between you and Selzy. Use POST for anything carrying a key or a recipient address. There is no per-key scope, so treat the key as root on the account.

Enabling API access

API access is off by default. Open Settings › Integration and API › API Access, turn it on, then click Show Full beside the key, which prompts for your registration password.

The mandatory platform parameter

If you are building an integration Selzy will list, its guidelines require a platform parameter on each API call, a Latin-letters-only identifier for your system, agreed in advance with a Selzy manager. Example: ...&title=***&platform=MySite.

Rate limits

Selzy layers a global account ceiling under per-method caps, then adds a daily ceiling for new accounts. All three bite in the same integration.

The workarounds are unglamorous. For contact sync, stop looping subscribe–importContacts does bulk create-and-update in one call and leaves the 300/minute band entirely. For transactional volume, sendEmail at 60 calls/minute under a 1,000/day ceiling is not a transactional pipe; that is what the UniOne relay is for, quoted at up to 150,000 emails/hour, see SMTP settings. And because the cap keys on IP as well as key, workers behind one NAT gateway share one 1,200/minute budget. Rate-limit centrally.

Official SDKs

This is the shortest section on the page because there is almost nothing in it. Selzy publishes no client library for api.selzy.com in any language. The one installable piece of Selzy-authored code is a WordPress subscription plugin, a product integration, not an SDK.

Notable community SDKs

There are none worth naming, and that absence is itself a trap. Package registries return libraries for UniSender, a separate company whose API exposes identical method names. Installing one appears to work at the call-signature level while its default base URL sends your key to the wrong vendor. The only check that matters: which host does it default to?

Endpoints reference

The surface is a flat method list, not a REST resource tree, so read it by task. Full parameter tables live in the official Selzy API reference.

Code examples

All snippets assume a key from Settings › Integration and API and a confirmed sender address. Nothing needs a library beyond an HTTP client.

Authenticated ping with curl

There is no ping or whoami method, so getLists is the cheapest proof a key works, and it shows why you must inspect the body, not the status code.

curl -sS -X POST https://api.selzy.com/en/api/getLists \
  -d format=json -d api_key="$SELZY_API_KEY"

# OK:   {"result":[{"id":112233,"title":"Newsletter"}]}
# Bad:  {"error":"unknown api_key","code":"invalid_api_key"}  <- still HTTP 200

Send an email, then register a webhook

import requests

BASE = "https://api.selzy.com/en/api"   # unversioned; lang code sits in the path

def call(method, **params):
    params.update(format="json", api_key=API_KEY)
    data = requests.post(f"{BASE}/{method}", data=params, timeout=30).json()
    if "error" in data:                 # HTTP 200 even on failure
        raise RuntimeError(f"{data.get('code')}: {data['error']}")
    return data["result"]

sent = call("sendEmail",
            email="john@example.com",
            sender_name="Acme",
            sender_email="hello@yourdomain.com",  # confirmed sender only
            subject="Your order is on its way",
            body="<h1>Hello, World!</h1>",
            list_id=112233,                       # drives the unsubscribe link
            track_read=1, track_links=1)
            # platform="MySite" <- required on EVERY call if you want a listing
print("queued email_id:", sent[0]["id"])

# Register the outbound hook once at deploy time, not per request.
call("setHook", hook_url="https://example.com/hooks/selzy",
     event_format="json_post_gzip", **{"events[]": "email_status"})

Minimal self-hosted MCP wrapper

With one credential and no OAuth, the bridge from MCP tool call to Selzy method is close to mechanical. Extending this skeleton across the method list is copy-and-adjust work.

import os, httpx
from mcp.server.fastmcp import FastMCP

BASE = "https://api.selzy.com/en/api"
KEY = os.environ["SELZY_API_KEY"]
mcp = FastMCP("selzy")

def call(method: str, **params):
    # One helper covers the whole API: flat methods, form body, JSON out.
    params.update(format="json", api_key=KEY)
    data = httpx.post(f"{BASE}/{method}", data=params, timeout=30).json()
    if "error" in data:
        raise RuntimeError(f"{data.get('code')}: {data['error']}")
    return data["result"]

@mcp.tool()
def list_contact_lists() -> list:
    """Return every Selzy contact list with its id and title."""
    return call("getLists")

@mcp.tool()
def add_contact(list_id: int, email: str) -> dict:
    """Add or update a contact in a Selzy list."""
    return call("subscribe", list_ids=str(list_id), **{"fields[email]": email})

mcp.run()

Common gotchas

Deprecations and changelog

Selzy publishes no public changelog or release-notes page anywhere on selzy.com, the help center runs to 17 categories and none is a changelog. Combined with the unversioned API, changes ship in place with no announcement channel. The entries below are dated findings from our own audit, not vendor announcements.

• August 19, 2026-Directory audit found no official or community Selzy MCP server in the official MCP registry, Glama, mcp.so or Smithery, and nothing MCP-related in selzy-dev on GitHub.
• August 19, 2026-selzy.com and unisender.com confirmed live as separate products with identical method names; a Selzy key authenticates against api.selzy.com only.
• August 19, 2026–selzy-dev/selzy-api-skill confirmed as an agent skill wrapping the REST API, with no MCP transport.
• August 19, 2026-UniOne confirmed to keep its own API changelog while Selzy publishes none; UniOne events are not Selzy events.

Watch the official Selzy API reference, and the UniOne API changelog if your sending path runs through the relay. Without a vendor feed, CI contract tests against getLists, subscribe and sendEmail are the cheapest early warning.

Frequently asked questions