LinkCensus API usage and limits
A free account gets 5 neighborhood lookups a month with up to five rows each. REST, the command line and the MCP server all draw on that one allowance.
The allowance
The allowance belongs to your account, not to a key. It covers neighborhood lookups only and resets at 00:00 UTC on the first day of each month; unused lookups do not carry over. Your current count and reset date are on your API keys page, and every lookup response repeats them in quota.
What counts
| Request | Uses a lookup? |
|---|---|
| List editions | No. Still needs a key and is rate limited. |
| Resolve a domain | No. Still needs a key and is rate limited. |
| Neighbor candidates | Yes, once admitted: also when it returns no rows, comes from cache or fails afterwards. |
| Invalid key or input, edition not loaded | No. |
| Turned away for rate or concurrency (429) | No. |
| Allowance already used up (429 quota_exceeded) | No. Lookups resume at the reset. |
| Timed out (504) | Possibly. Check your usage before trying again. |
Free and paid keys
| Key | Lookups a month | Rows per lookup |
|---|---|---|
| Free-tier key | 5 | 5 |
| Paid-tier key, with current seat access | 1,000 | 100 |
Any account can create a free-tier key at no cost. An account with current seat access can also create paid-tier keys, while the agent API is offered. Both kinds share one counter, and each key stops at its own limit: a free-tier key on a seat account still stops at 5 and returns five rows. If seat access ends, paid-tier keys fall back to the free limits. A seat does not guarantee API access; the terms have the details.
Website lookups
Lookups on linkcensus.com are counted separately. Using the API does not reduce what you can look up on the website, and browsing the website does not use API lookups.
Keys and resets
A key is shown once, when you create it. If you lose it, replace it: the old key stops working as soon as the new one exists. Replacing or revoking a key never resets the month's count, and adding keys does not add lookups. An account can hold up to ten active keys.
Reading results
Each row is a candidate from a dated edition: a domain near yours in the Common Crawl link graph, not a confirmed competitor. Shared linkers are counted among the top 200 retained for each domain, so a count is a floor. The total field counts candidates within the retained search set after your filters, not every similar site on the web. Keep the edition and ranking mode with any result you store, and check each candidate's own site before you classify it. The method page explains how neighbors are found, and the response fields list what each value means.