canonical: https://jentic.com/apis/host.io/hostio # Host.io API Jentic publishes the only available OpenAPI specification for Host.io API, keeping it validated and agent-ready. The Host.io API provides domain intelligence - DNS records, hosting details, scraped website metadata, outbound links, backlinks, and reverse lookups by IP, NS, MX, ASN, or backlink. Five endpoints cover both per-domain inspection and reverse domain search. Useful for security analysts, SEO researchers, and AI agents that need to enrich a URL with structured infrastructure data. ## For AI agents Look up DNS, hosting, links, and backlinks for any domain, plus reverse-lookup all domains sharing an IP, NS, MX, or ASN. ## Scope Does not handle WHOIS registrant data, SSL certificate inspection, or live HTTP probing - use for DNS, hosting, link, and reverse-domain lookups only. ## Capabilities - Resolve DNS records (A, NS, MX, TXT) for any domain in a single call - Fetch scraped website metadata including title, description, and tech stack hints - Pull outbound links from a domain's homepage for crawl mapping - List domains that share an IP, name server, MX, or ASN with a target domain - Get backlink counts and a sample of referring domains - Combine domain, DNS, IP, and link data in one full-domain lookup ## Use cases ### Phishing Domain Investigation Investigate suspicious lookalike domains by pulling DNS, hosting, and reverse-lookup data from Host.io. The agent calls GET `/full/{domain}` for the suspect, then reverse-lookups its IP via GET `/domains/{field}/{value}` to find every other domain on the same host. Surfaces clusters of related phishing infrastructure quickly. Example prompt: Call GET `/full/{domain}` for suspicious-bank-login.com, then GET `/domains/ip/{ip}` to list every domain sharing its IP. ### Sales Prospecting Enrichment Enrich an inbound lead's email domain with website metadata, hosting provider, and outbound link signals. The agent calls GET `/web/{domain}` for the title and description, GET `/related/{domain}` for related-domain counts, then formats the output for the CRM. Helps AEs qualify prospects before outreach. Example prompt: Pull website metadata and DNS records for the prospect's domain and write a summary into the CRM lead record. ### SEO Backlink Audit Audit referring domains to a target site by calling GET `/full/{domain}.` The endpoint returns backlink counts and sample referring domains in one shot, so an agent can build a quick competitive backlink overview without scraping. Useful for SEO assistants and site migration audits. Example prompt: Fetch GET `/full/{domain}` for the target site and emit the backlink count plus the top 10 referring domains. ### AI Domain Intelligence Agent via Jentic Plug Host.io into an AI security or research agent through Jentic so the agent can answer domain questions without juggling auth or building reverse-lookup logic. Jentic stores the API token in your Jentic One instance and exposes each Host.io operation by intent search. Example prompt: Search Jentic for 'list domains on same IP', load the schema, and execute against IP 1.2.3.4 to return all sharing domains. ## Key endpoints | Method | Path | Description | | --- | --- | --- | | GET | `/web/{domain}` | Get scraped website metadata | | GET | `/dns/{domain}` | Get DNS records (A, NS, MX, TXT) | | GET | `/related/{domain}` | Get related-domain counts | | GET | `/full/{domain}` | Get full domain report combining DNS, IP, links | | GET | `/domains/{field}/{value}` | Reverse-lookup domains by IP, NS, MX, ASN, or backlink | ## Key resources - **Domain Info** — Per-domain metadata, DNS, related counts, and full domain reports. - **Domain Search** — Reverse-lookup endpoint that lists domains sharing a field value (IP, NS, MX, ASN, backlink). ## Why Jentic - **Setup:** Wiring Host.io by hand means choosing among its bearer, basic, or query-token auth, keeping the host.io/api host straight across the lookup endpoints, and handling errors yourself. Through Jentic you install once, import the Host.io API from the API Directory, store the token once, and your agent calls it. - **Permission scoping:** Host.io serves read-only DNS, hosting, link, and reverse-domain lookups, so scope your agent to the lookup operations it needs, such as a domain web profile or reverse lookup by field. You choose which calls are in the allowed set, and every operation here is a read, so nothing mutates the data. - **Credential handling:** Your Host.io token is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context. - **Discovery method:** Agents search Jentic by intent such as 'reverse lookup domains by IP' or 'get DNS records for a domain', and Jentic returns the matching Host.io operation with its input schema so the agent calls the right endpoint without browsing the reference docs. ## Related APIs - **FullContact API** — Enriches contacts and companies with people-level signals beyond infrastructure data. - **Clearbit API** — Adds firmographic and technographic enrichment on top of a domain. - **Apiip IP Data API** — IP-first data provider with detailed geo and network associations. ## FAQ ### Why is there no official OpenAPI spec for Host.io API? Host.io does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call Host.io API via structured tooling. It is validated against the live API and kept up to date. Get started with Jentic One, the self-hosted execution layer. ### What authentication does the Host.io API use? Three options are supported: bearer token (Authorization: Bearer ), HTTP basic, or an API key in the query string. Jentic stores the credential in your Jentic One instance and injects whichever scheme the call requires. ### Can I find every domain hosted on a given IP with the Host.io API? Yes. GET `/domains/{field}/{value}` with field=ip and the IP address as the value returns the list of domains observed on that IP. The same path supports field=ns, mx, asn, and backlink for other reverse lookups. ### What are the rate limits for the Host.io API? Host.io rate limits are tied to plan tier - free plans are heavily throttled and paid plans scale up to thousands of requests per day. Check your plan in the Host.io dashboard and back off on 429 responses. ### How do I look up DNS records for a domain with the Host.io API through Jentic? Run pip install jentic, search for 'get DNS records for domain', load the GET `/dns/{domain}` schema, and execute. Jentic handles the auth header and returns the structured DNS payload. ### Does the Host.io API give me both backlinks and outbound links? Yes. The `/full/{domain}` endpoint returns scraped website metadata (title, description, outbound links sample) and backlink counts in a single response, so an agent can pull both link directions in one call. ### Can I limit what my agent is allowed to do with the Host.io API? Yes. Because you run Jentic One yourself, your own rules decide which Host.io operations and credentials the agent may use, so you can allow only the lookups it needs, such as GET `/web/{domain}` for a website profile, GET `/dns/{domain}` for DNS records, or GET `/domains/{field}/{value}` for a reverse lookup by IP, NS, MX, or ASN. Every Host.io operation is a read, so nothing it calls mutates any data. Keep the reverse-lookup and full-report endpoints out of the allowed set if the agent only needs single-domain DNS or metadata.