Skip to main content
Helium shares Horizon’s exact error envelope, HTTP status codes, and request_id convention — see Horizon’s Errors & Rate Limits page for the full shape and status-code table (400/401/402/422/429/502/503). The same envelope applies to every Helium REST and MCP call.

​
What’s different for Helium

No cache-eviction support. Horizon’s DELETE /v1/cache endpoint does not apply to any Helium endpoint — Helium’s research results aren’t cached in the first place (see Credits & Pricing), so there’s nothing to evict. All billed endpoints charge on a miss. Helium has no equivalent to Horizon’s “charged on success only” person.email exception — every one of search_investors, enrich_investor, and research_company charges its full listed price even on a clean “nothing found” result.

​
Rate limits

Rate limits apply per API key, using the same tiers as Horizon (10 requests/minute on a free-trial key, 60/minute on any paid pack). If your workspace has installed both Horizon’s and Helium’s Slack apps, each app’s own dispatch key has its own independent rate-limit bucket — hammering one doesn’t eat into the other’s. Credits, however, are shared tenant-wide across every key and both products — a rate limit is per-key, a credit balance is per-account.