Hosted fetch - Hermai

Hosted fetch lets you call registered Hermai endpoints through the hosted API when they are available for hosted execution. Send a site, an endpoint, and optional params; Hermai runs the request and returns the structured result. Use hosted fetch when you want production execution through Hermai instead of downloading a schema and calling the upstream site yourself.

Basic request

export HERMAI_API_KEY="hm_sk_..."

curl -sS -X POST "https://api.hermai.ai/v1/fetch" \
  -H "Authorization: Bearer ${HERMAI_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "site": "semanticscholar.org",
    "endpoint": "get_paper",
    "params": {
      "paper_id": "ARXIV:1706.03762",
      "fields": "paperId,externalIds,title,authors,venue,year,referenceCount,citationCount,openAccessPdf"
    }
  }'

Response:

{
  "success": true,
  "data": {
    "paperId": "204e3073870fae3d05bcbc2f6a8e263d9b72e776",
    "title": "Attention is All you Need",
    "year": 2017,
    "citationCount": 183000
  },
  "meta": {
    "site": "semanticscholar.org",
    "endpoint": "get_paper",
    "method": "GET",
    "source": "gateway",
    "latency_ms": 1234,
    "credits_used": 1,
    "credits_remaining": 999,
    "cached": false
  }
}

Credit cost

credits_used reflects the weighted cost of the call:

A standard request costs 1 credit.
Some higher cost sites, such as large consumer marketplaces and certain listing or travel portals, cost 5 credits.
Endpoints that return multiple results (such as a comparison set) bill per result.
Only successful requests are billed. Failed requests are free.
Each response reports the exact credits it used (meta.credits_used).

Request body

Field	Type	Required	Description
`site`	string	Yes	Registered site domain, such as `semanticscholar.org`
`endpoint`	string	Yes	Endpoint name from the schema, such as `get_paper`
`params`	object	No	Endpoint parameters. Values are strings, numbers, booleans, arrays, or objects.

Finding endpoints

Browse public schema cards without an API key:

curl "https://api.hermai.ai/v1/schemas/semanticscholar.org"

Pull the full package when you need URL templates, request details, and the full parameter contract:

curl -H "Authorization: Bearer ${HERMAI_API_KEY}" \
     -H "X-Hermai-Intent: using Semantic Scholar metadata for citation enrichment" \
     "https://api.hermai.ai/v1/schemas/semanticscholar.org/package"

You can also use the catalog API when you want your own agent or server to call upstream sites directly.

Citation metadata examples

Hosted fetch is useful for publication and repository metadata workflows. Common registered routes include:

Site	Example endpoint	Typical lookup
`semanticscholar.org`	`get_paper`	Semantic Scholar, DOI, PubMed, Corpus, or arXiv IDs
`openalex.org`	`works_search`, `get_work`	Works by title, DOI, or OpenAlex ID
`crossref.org`	`filter_work_by_doi`, `get_work_by_doi`	DOI metadata
`pubmed.ncbi.nlm.nih.gov`	`search_pubmed`, `summarize_pubmed`	PubMed search and PMID summaries
`europepmc.org`	`search`, `get_by_ext_id`	Europe PMC literature metadata
`datacite.org`	`get_doi`, `search_dois`	DOI metadata for datasets and preprints
`unpaywall.org`	`get_by_doi`	Open-access status and links
`huggingface.co`	`get_model_by_owner_repo`, `get_dataset_by_owner_repo`, `get_paper_repos`	Model, dataset, and paper-linked repository metadata
`github.com`	`GetRepository`, `SearchRepositories`	Repository metadata
`sciencedirect.com`, `nature.com`	`metadata_by_doi_crossref`, `metadata_by_doi_openalex`	DOI metadata via Crossref or OpenAlex

For publisher pages such as ScienceDirect or Nature, use DOI metadata routes. Hermai does not need to scrape protected article pages to return citation metadata.

Errors

Errors use the standard API envelope:

{
  "success": false,
  "error": {
    "code": "MISSING_ENDPOINT",
    "message": "The 'endpoint' field is required"
  }
}

Common error codes include:

Code	Meaning
`INVALID_JSON`	Request body is not valid JSON
`MISSING_SITE`	`site` is required
`MISSING_ENDPOINT`	`endpoint` is required
`INSUFFICIENT_CREDITS`	The workspace does not have enough credits for hosted execution
`FETCH_FAILED`	Hermai could not complete the upstream request
`RESOURCE_UNAVAILABLE`	A hosted resource needed by the endpoint is not currently available

Running out of credits

When a workspace is out of credits, POST /v1/fetch returns 402 and the error carries a structured upgrade path so an agent can act on it without parsing the message. upgrade_to names the target plan or add-on and upgrade_url links to checkout:

{
  "success": false,
  "error": {
    "code": "INSUFFICIENT_CREDITS",
    "message": "insufficient credits",
    "upgrade_to": "pro",
    "upgrade_url": "https://hermai.ai/pricing"
  }
}

When to use catalog instead

Use GET /v1/catalog/{domain} or GET /v1/schemas/{site}/package when you want the schema recipe and plan to execute requests yourself. Use POST /v1/fetch when you want Hermai to execute a supported registered endpoint and return the result.

​Basic request

​Credit cost

​Request body

​Finding endpoints

​Citation metadata examples

​Errors

​Running out of credits

​When to use catalog instead