Omnisend vs Sequenzy

Omnisend 81

Graded on the REST API at api.omnisend.com, with the hosted MCP server where a line names MCP. Statuspage at status.omnisend.com with an API component and incident history (20). The history feed's newest incident is still 26 May 2026 on 2 November, so the 90 days from 4 August are clean (30). Rate limits published per endpoint, 400 requests a minute per brand by default and down to 10 a minute and 55 a day for analytics reports (15). A 429 returns a problem document, and some endpoints add retryAfter in seconds. No Retry-After header, backoff guidance or idempotency keys were found. POST /contacts upserts on the email identifier and only a draft campaign can be sent, so a repeated send returns 409 (8). No SLA found, and the terms say scheduled or unscheduled downtime may occur (0). Version 2026-03-15 is the current version, but the Campaigns API definition is labelled 2026-preview and the changelog announced the Forms API as beta on 24 April 2026, so 8 of 10.

Sequenzy 38

Graded with the hosted lines. No status page was found; none is linked from the site, llms.txt or docs, and status.sequenzy.com doesn't resolve (0). With no history to read, the incident line takes 5. 429 responses carry RateLimit-Limit and RateLimit-Remaining headers for a per-minute policy, and some routes state numbers (20 requests a minute per workspace for AI copy), but no table of limits per key was found (8 of 15). 429s carry Retry-After, sends take an Idempotency-Key, a reused key with a different body returns IDEMPOTENCY_KEY_REUSED, and the MCP docs say a retry hint alone doesn't make a write safe to repeat (15). No SLA found (0). No beta label on the API or MCP server (10). Total 38.

Omnisend 39

The newest dated change to the agent surface is the Content Translations API's GET /content-translations/languages operation page, stamped 30 October 2026 and not in the 104-operation index read on 9 October. The MCP reference pages carry 1 September 2026 stamps, and the newest product changelog entry that names the API or MCP is 10 July 2026 (30). The product changelog's newest entries are 1 and 24 September 2026, neither naming the API or MCP, and the docs revisions on 5 August, 26 August and 1 September (per the 9 October check) and the 30 October operation page give one dated API change, not three (0 of 20). A public changelog with a roadmap tab, a support address in the docs and live chat and email support on every plan per the pricing page. No developer forum was found and we saw no reply times (9 of 15). No official SDK was found, and a search of the official MCP registry for Omnisend returned no server on 2 November (0 of 15). No package to assess (0 of 10).

Sequenzy 78

sequenzy 2.1.56, @sequenzy/mcp 0.0.246 and @sequenzy/cli 0.0.202 were all published on 6 November 2026 (30). 18 SDK, 105 MCP and 93 CLI releases in the 90 days from 8 August, and dated changelog entries on most days (20). A closed service with a public changelog and support answered by the cofounders per the about page. GitHub issues weren't read, as the GitHub API refused our requests for its rate limit (12 of 15). Listed in the official MCP registry as io.github.polnikale/sequenzy-mcp, but the entry is at 0.0.36 against npm's 0.0.246, and the TypeScript SDK is current (10 of 15). MIT packages released daily, the MCP server and CLI still at 0.0.x (6 of 10). Total 78.

Omnisend 79

Every operation page is served as Markdown with its OpenAPI 3.0.0 definition, security schemes and scopes. No single downloadable OpenAPI file was linked from the pages read, and a Postman collection is linked instead, so 22 of 25. api-docs.omnisend.com/llms.txt indexes the guides and all 105 operation pages as Markdown, one more than on 9 October (10). Descriptions state the purpose, scopes, rate limit and state rules, such as that only a draft campaign can be sent and a sent one must be copied. Few say when not to use an endpoint (15). The two definitions read in full use required fields, enums and typed parameters. The rest were read only as index lines (11). Each operation lists its own 400, 401, 402, 403, 404, 409, 410, 429 and 500 responses with schemas and examples (13). Dated versions in a header and migration guides from versions 3 and 5, but no API changelog. API changes appear only now and then in the product changelog (8).

Sequenzy 95

OpenAPI 3.1 at docs.sequenzy.com/openapi.yaml with 349 paths and 475 operations, all described (25). llms.txt on both hosts, llms-full.txt, auth.md, agents.md and Markdown twins of the docs (10). Operation and tool descriptions give purpose, the scope each needs and the alternative, such as the deprecated generate-sequence alias (18 of 20). Typed inputs, and tools reject undeclared arguments with an error naming the supported ones (13 of 15). Errors on nearly every operation (401 on 442, 404 on 330, 400 on 290) with examples, and a structured error with code, howToFix and docsUrl for tools (14 of 15). Version in the path and spec, and a dated changelog (15). Total 95.

Omnisend 79

The MCP server lists four tools in front of the 105 operations its docs table names, with search, tool_schema and tool_documentation loaded on demand. We couldn't read the tool definitions without an account, and no field selection was found on the REST API (22 of 25). Cursor pagination with limit up to 250, sort, direction and filters on list endpoints (20). RFC 9457 errors with field-level codes, every validation failure returned at once and a trace ID (20). No idempotency keys. Contact creation upserts on email, a campaign can be sent only from draft, and the MCP docs mark 47 of 105 operations read-only in a table, while the v2 server splits read, create, update and delete into separate tools. Tool annotations were not read (10). List defaults are sensible and two headers are required on every call. No official SDK was found (7).

Sequenzy 69

The MCP tool reference lists about 306 tools, the over-30 band, and no toolsets, tool search or dynamic loading was found (5 of 25). List endpoints paginate and filter, and contact timelines use cursors (20). Errors carry a code, a human message, a fix and a docs link, with retryAfterSeconds when the API sent Retry-After (20). Idempotency keys on sends and event imports; MCP readOnlyHint and destructiveHint annotations weren't found in the published reference (14 of 20). Sensible defaults with a selected workspace; one official SDK (TypeScript) plus a CLI (10 of 15). Total 69.

Omnisend 57

API keys are named, shown once and sent in a header. OAuth uses the authorisation code grant with per-resource read and write scopes, but credentials need a request form, no PKCE is documented and the token in the docs never expires unless revoked. The MCP server uses OAuth with dynamic client registration. Whether an API key can be scoped or rotated was not found (22). The MCP consent screen sets an access level with a read-only preset, and scopes split read from write. No approval or confirmation step before a campaign send was found, and the terms put approval of each agent action on the customer (13). The MCP docs warn against enabling two brand connectors in one chat and advise read-only access. No guidance on untrusted content in contact or form data was found (4). The app records API errors under API Issues. No log of successful calls or audit log endpoint was found (6). security.txt names a contact and a bug bounty policy whose scope includes api.omnisend.com, and the DPA states annual third-party penetration tests. No SOC 2 or ISO 27001 statement was found on the pages read (12).

Sequenzy 67

Workspace and account API keys with fine-grained permission scopes, presets and explicit *:delete rights, revocable in settings, plus an OAuth service_auth flow for agents with user confirmation (30). Read-only and drafts-only presets let an agent prepare mail without sending, and account keys keep the user's workspace role (20). The agent inbox and reply tracking give the agent inbound mail, and no prompt-injection guidance was found in the MCP, permissions or inbox docs (4 of 15). The DPA lists administrative audit logs and MCP events report replies and bounces; no per-call API log for the customer was found (8 of 15). A responsible disclosure address on the security page, no security.txt (404), bug bounty or certification (5 of 20). Total 67.

Omnisend 30

No x402, MPP or L402 in the API documentation or the pricing page. The 402 on the send campaign endpoint is a plan payment error (0). Plan prices are public and scale with contacts through a slider, with Standard at 500 contacts and Pro at 2,500 contacts shown at a three-month discount. Nothing is priced per API call (10). The Free plan has 250 contacts and 500 emails a month, and the page says no credit card is required (20). A person has to sign up in a browser and create a key or approve OAuth (0).

Sequenzy 40

No x402, MPP or L402 (0). Prices are public as volume tiers from $19 for 15,000 emails to $2,999 for 5 million, without a per-email overage rate (10 of 20). Free plan of 2,500 emails a month with no card (20). Agents can register through service_auth, but the user has to confirm a code in a Sequenzy browser page, and plan payment is through Stripe (10 of 20). Total 40.