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NPM Symbol Export Verifier
x402
NPM Symbol Export Verifier is a paid API for AI agents from 401-chi.vercel.app, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-13).
Checks whether a named symbol is publicly exported by a specific npm package version, returning existence, export kind, and certainty level.
Price / call$0.003
Success—
StatusUnknown
How this service works
Verify whether a named API symbol is publicly exported by an exact npm package version. Returns structured existence, export kind, certainty, and package-artifact evidence.
Output
Returns a structured JSON object with a query echo (ecosystem, package, requestedVersion, symbol), a result block (exists: boolean, exportKind: named/default/namespace/type/unknown/null, certainty: verified/inconclusive), an evidence array with source artifacts and package version details, and a retrievedAt timestamp.
Example use cases
Validate dependency before code generation
“Before you generate code using it, check if `useQuery` is actually exported by `@tanstack/react-query` at version 5.0.0 — I want to make sure it exists as a named export.”
Debug missing export after upgrade
“I upgraded `axios` to version 1.6.0 and now my import is breaking — can you check if `AxiosRequestConfig` is still exported from that version?”
Audit library API surface for a specific version
“I need to know if `parseISO` is a named export in `date-fns` at version 3.0.0 — can you verify that and tell me how certain the result is?”
Technical details
Endpoint
POSThttps://401-chi.vercel.app/api/v1/symbolWhen to prefer
Use this endpoint when you need to programmatically verify that a specific named symbol (function, class, type, constant) is publicly exported by a pinned npm package version before generating code, validating dependency compatibility, or auditing API surface changes across versions. It is preferable over manual registry inspection or documentation lookups when certainty and structured evidence are required by an automated agent workflow.
Side effects
- Package version not found on npm registry — returns inconclusive certainty or error
- Symbol does not match identifier pattern (must start with letter, $, or _) — validation error
- Invalid semver version string — rejected by input schema
- Package name does not conform to npm naming rules — schema validation failure
- Ecosystem value other than 'npm' — rejected (only npm supported)
- Network or registry fetch failure — may return inconclusive certainty with partial evidence
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| symbol | string | |
| package | string | |
| version | string | |
| ecosystem | string |
Tags
x402
Reviews
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