Request external human input from LangGraph.

A LangGraph node creates a Fangst request when the graph needs a person outside the agent runtime. Share the hosted URL, then resume with the response.

Start free See the API example

From API call to structured result.

Create the requestSoftware or an AI agent defines the fields and receives a hosted URL.
Share the URLA person opens the Fangst page and provides the requested input or files.
Read the resultFangst returns structured data through the API or a signed webhook.

Call Fangst from a graph node.

Store the Fangst request id in graph state and poll it from a resumable node or continue from your webhook handler.

Create

def request_supplier_details(state):
    request = fangst.create_request(
        title="Supplier details",
        fields=state["missing_fields"],
        metadata={"thread_id": state["thread_id"]},
    )
    return {"fangst_request_id": request["id"],
            "human_url": request["hosted_url"]}

Completed result

{
  "status": "completed",
  "response": {
    "company_name": "Northstar AS"
  }
}

Map Fangst onto durable LangGraph state.

Use Fangst when the respondent is outside the graph runtime and needs a normal hosted page. The graph keeps identifiers and status in state; Fangst handles the public interaction and returns the structured response.

Create once

Create the request in a node with an idempotency key derived from the graph thread and logical step.

Persist identifiers

Store the Fangst request id and hosted URL in graph state before the run waits or exits.

Resume deliberately

Poll from a resumable node or route a verified completion webhook back to the correct thread before updating state.

Use REST, MCP, polling, or webhooks.

Software uses the HTTP resources directly. Authorized AI agents can use the same API or intention-oriented Fangst MCP tools.

POST/v1/requestsCreate a hosted request and receive its URL.

GET/v1/requests/:idRead request status and configuration.

GET/v1/requests/:id/submissionsRead completed responses.

MCPrequest_human_inputLet an authorized agent create the request.

MCPget_human_inputLet the agent read the completed response.

Fangst runs the hosted interaction.

Hosted page

Responsive pages, clear sender context, validation, private or shared links, expiry, and submission limits.

Structured result

Typed values, authenticated file downloads, correlation metadata, timestamps, and stable response ids.

Reliable delivery

Polling, signed webhooks, retries with backoff, delivery history, idempotency, and replay.

Pay for completed interactions. No subscription.

Start with $1 free. Add funds from $10. Links, polling, webhooks, and abandoned requests do not use the main billable unit.

See pricing

Give your software a way to ask people.

Create the hosted interaction through Fangst and receive the structured result back.

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