Head to head · Seo keywords · October 2026 research run
Moz API vs Similarweb
Similarweb and Moz API score within a point of each other on agent readiness, 46 (D) and 45.3 (E). Moz API leads on reliability, agent ergonomics and payments & pricing. Both do seo keywords.
Which one, for what
Moz API E
Good for Agents that need Domain Authority, backlink lists, link intersects, keyword volume and difficulty, search intent and ranking keywords at a low entry price, on a read-only data set.
Ahead on
- Reliability, 42 against 35
- Agent ergonomics, 74 against 67
- Payments & pricing, 20 against 5
Watch for
No working public status page was found, and moz.statuspage.io reports the Moz Status page as inactive
Good for Traffic and engagement estimates, traffic channel mix and keyword click data for domains an agent doesn't own, with app, company and retail data on the same key.
Ahead on
- Schema & documentation, 63 against 50
- Security & auth, 52 against 38
- Maintenance & community, 33 against 28
Watch for
API and MCP access need a Business, Enterprise or API-only plan bought through sales. The FAQ says there's no API test without a subscription
Score by category
| Category | Weight this run | Moz API | Similarweb | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 42 | 35 | Moz API +7 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 50 | 63 | Similarweb +13 |
| Agent ergonomics | 13%16.2 | 74 | 67 | Moz API +7 |
| Security & auth | 14%17.5 | 38 | 52 | Similarweb +14 |
| Payments & pricing | 10%12.5 | 20 | 5 | Moz API +15 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 28 | 33 | Similarweb +5 |
| Transparency & trust | 7%8.8 | 59 | 60 | Similarweb +1 |
| Negative events | ≤15 | 0 | 0 | |
| Total | 45.3 · E | 46 · D |
Facts side by side
| Fact | Moz API | Similarweb |
|---|---|---|
| Kind | HTTP API | HTTP API |
| Vendor | SEOmoz, Inc. | Similarweb Ltd. |
| Hosted endpoint | https://api.moz.com/jsonrpc | https://api.similarweb.com |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Paid |
| x402 | no | no |
| Licence | Proprietary service under the Moz API General Conditions (effective 12 August 2026 for new subscribers). Displaying Moz data to others requires attribution under the API legal page | Proprietary service under Similarweb's terms of use |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-08-14 | 2026-09-24 |
| Terms last updated | 2026-08-12 | 2025-03-19 |
| Privacy policy last updated | 2025-04-08 | 2026-06-30 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
Verdicts
Moz API
The JSON-RPC API documents every error code, its rate limits and the row cost of each method, and failed validation uses no quota. No working status page, SLA, machine-readable spec or official SDK was found. Tokens carry no scopes, and the free plan needs a credit card.
Similarweb
The V5 API returns traffic estimates, keyword clicks and SERP positions with selectable metrics, and the hosted MCP server accepts OAuth with a read scope. Access needs a Business, Enterprise or API-only subscription sold through sales, with no API trial, public price per credit or public status page found.
Before you call either
Moz API
- Send a request
idof at least 24 characters (letters, numbers and hyphens). A UUID works. Shorter ids are rejected with -32654. - Stop on a 401. Ten 401 or 403 responses in five minutes block the caller for 30 minutes.
- On 429 with code -32658 wait the
Retry-Afterseconds. On code -32650 no wait time is given, so back off exponentially. - Call
quota.lookup(free) before large pulls. List methods charge one row per result, andlimitis capped at 50 on link lists. - Poll
async.call.lookupfordata.keyword.serp.generate, and collect the result within 20 seconds of first seeing it complete.
Similarweb
- Send the key in the
api-keyheader. The capabilities endpoint documents?api_key=in the URL, which puts the secret in logs - Stay under 10 requests a second. A 429 can also mean the monthly credit allowance is spent, so call
/capabilities(free) before retrying - Pass domains in lower case without
www.or a path. The docs list 401 as data not found for a malformed domain - Request only the metrics, countries and months needed. Credits multiply across domains, metrics, countries and periods, and daily granularity costs about 30 times monthly
- Website keywords accept monthly granularity for the last three months only, and
positionisn't returned for worldwide
Questions
Which is better for AI agents, Moz API or Similarweb?
Similarweb and Moz API score within a point of each other on agent readiness, 46 (D) and 45.3 (E). Moz API leads on reliability, agent ergonomics and payments & pricing.
Do Moz API and Similarweb need an API key?
Moz API needs an API key. Similarweb takes an API key or an OAuth sign-in.
Can an agent call Moz API and Similarweb without installing anything?
Yes. Moz API has a hosted endpoint at https://api.moz.com/jsonrpc and Similarweb at https://api.similarweb.com.
Other comparisons with Moz API or Similarweb
Machine-readable
- This page as Markdown
/compare/moz-api-vs-similarweb.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/moz-api.json·/api/v1/tools/similarweb.json - From a terminal
anchor compare moz-api similarweb(the CLI) - Over MCP
compare_tools {"a": "moz-api", "b": "similarweb"}at/mcp, no key