Mailchimp Marketing API vs Sequenzy

Mailchimp Marketing API 72

Graded on the hosted REST API with the hosted lines. status.mailchimp.com lists an API component for each of 21 data centres and keeps event history by month, re-read on 4 November (20). In the 90 days from 6 August 2026 the marketing events are campaign links returning 500 errors on 13 August, delayed audience updates on 11 September, cropped images disappearing in campaigns from 9 October, and access issues on some app pages "for some Mailchimp users" on 27 to 29 October. Each hit one function or some users, none names the API component, and November has none, so minor only (20). The loss of click tracking from 3 to 4 August ended before the window. The three Transactional delays belong to the Mailchimp Transactional listing. The docs give 10 simultaneous connections per user, a 120-second timeout and 500 pending batches, with no per-minute figure (12 of 15, partly met). 429 is documented with its cause. The official Python library's README says it retries 408, 409, 429 and 5xx with exponential backoff, two retries by default. No Retry-After header, idempotency key or safe-retry guidance for writes was found in the docs, so backoff alone (10). No SLA found (0). Version 3.0 is generally available, and the Audiences endpoints are beta (10). 20 + 20 + 12 + 10 + 0 + 10 = 72.

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.

Mailchimp Marketing API 46

API keys are named, several to an account, revocable, and bounded by the creating user's level. A key has full account access, and the docs say there is no read-only key and no per-endpoint limit. Keys made from 22 June 2026 expire after one year per the help centre. OAuth 2 uses the authorisation code grant with no scopes, and its tokens never expire. Credentials travel in a header, not the URL (20). No read-only mode. send-checklist, actions/test, actions/unschedule and actions/cancel-send exist, with no approval step before a send or a permanent contact delete (6). The API returns contact fields, conversation messages and survey answers, which are untrusted text, and no guidance on prompt injection was found (2). /authorized-apps lists the OAuth apps on an account and each response carries a request id. No API call log or audit log was found in the docs we read (4). A responsible disclosure programme with no rewards, a security.txt with a contact and no Expires field, SOC 2 reports, ISO 27001, regular penetration tests and optional two-factor sign-in. No public advisory feed found (14).

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.

Mailchimp Marketing API 76

An OpenAPI 3.1.1 file with all 297 operations is public on the API host, and the docs site serves a 1.2 MB copy (25). llms.txt at each level of the docs and a Markdown copy of every page at the URL plus .md (10). Every operation has a description, averaging about 60 characters. They say what a call does and seldom when not to use it, and four agent skills cover consent, OAuth, webhooks and bulk jobs (10). The smaller file carries 498 enums and required fields on request bodies. Merge fields and event properties are free-form objects (12). The API's own file has examples throughout and a default error response on every operation, and the docs have an error glossary. The docs-site copy lists only 200 and 204 responses (12). The version is in the path and has been 3.0 since 2016. The public changelog's newest entry is 19 August 2025, so key expiry from 22 June 2026, webhook signing and the new client libraries are not in it, and the specification's version label is 0.1.0-dev (7).

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.

Mailchimp Marketing API 25

No x402, MPP or L402 (0). Plan prices are public without a login, from $13 a month for Essentials, $20 for Standard and $350 for Premium with USD selected, rising with contacts through a selector. Nothing is priced per API call (10). The Free plan has 250 contacts and 500 sends a month with no time limit. We could not confirm that signup asks for no card, and the 14-day trial of a paid plan needs payment details, so 15 of 20. A person signs up in a browser and creates a key or approves 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.

Mailchimp Marketing API 68

Release 1.0.3 of the TypeScript, Python and Go client libraries, the first tag in each, is dated 5 October 2026, 30 days before this check (30). The TypeScript library's 1.0.03 of 13 October changes only version strings and the lockfile, so it counts half and doesn't set recency. Dated releases in the 90 days from 6 August include the CLI's 0.0.212 and 0.0.213 and Swift 1.0.0 on 18 September, Java 1.0.0 and C# 1.0.0 and 1.0.1 on 21 September, and 1.0.3 across the libraries on 5 October (20). The API changelog has no entry in that time. A public changelog whose newest entry is 19 August 2025, an API help address, and a help centre article saying support is not trained for in-depth API questions. We saw no public issue replies (5 of 15). Nine official client libraries generated from the current specification, with the TypeScript package absent from npm on 8 October (8 of 15, partly met). Each repository has a workflow that compiles and tests, whose results we could not see, and release 1.0.3 removed the LICENSE and NOTICE files added on 18 September (5 of 10, partly met). 30 + 20 + 5 + 8 + 5 = 68.

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.

Mailchimp Marketing API 74

Closed service with published terms, an API Use Policy and a named contracting entity. The client libraries declare Apache-2.0 in package metadata (15). A data processing addendum effective 26 September 2024 covers deletion or return on termination without a stated period, and the Intuit Global Privacy Statement of 9 March 2026 is the privacy document. The terms let Mailchimp use inputs and outputs of its AI functions, customer data included, for machine learning, with a preference in account settings. No retention periods for marketing data were found (18). No deprecation policy was found. The API Use Policy says the APIs can change by a posting or an email. Dated notices exist, such as key expiry from 22 June 2026 in the help centre (8). A sub-processor list with locations is public and was last updated on 29 February 2024, and the security page places Mailchimp's own servers in United States data centres (14).

Sequenzy 67

A closed service. The SDK, MCP server and CLI are MIT on npm. The terms (30 June 2026) don't name the contracting entity in their text or a governing jurisdiction; the footer names Nic Tech Solutions, LLC (15 of 30). Privacy policy of 16 September 2026 and a public DPA agree on processing, and the terms say data is deleted within 30 days of termination (24 of 30). Deprecated endpoints are marked and kept as compatibility aliases; no written deprecation policy with notice periods (10 of 20). The DPA names its core sub-processors with their purpose; data locations aren't stated (15 of 20). Total 64.