> ## Documentation Index > Fetch the complete documentation index at: https://docs.particle.pro/llms.txt > Use this file to discover all available pages before exploring further. # Look up people and companies by external identifier > Resolves external identifiers — LinkedIn slugs, social handles, company domains, stock tickers, SEC CIKs, Wikidata QIDs — to the people and companies that carry them. It is the reverse of GET /v1/people/{slug}/external-links and GET /v1/companies/{id}/external-links. Pass a comma-separated `identifier` list (up to 100 per call); `platform` is optional, so a handle with no known source still resolves. A full profile URL works in place of a bare identifier and the platform is inferred from it, and the stored form is matched for you — pass `satyanadella` or the profile URL, not `in/satyanadella`. Each result echoes the input identifier and carries a `matches` array, because an identifier is not unique to an entity: a LinkedIn profile claimed by two duplicate person records resolves to both, and `match_count` reports the total. Unresolved identifiers come back with an empty `matches`, so a bulk caller never has to reconcile a shorter response against a longer request. Correlate by the echoed `identifier` rather than by position, since duplicate identifiers collapse to one result. Use GET /v1/entities/search instead when you have a name rather than an identifier, and GET /v1/podcasts/lookup or GET /v1/podcasts/episodes/lookup for podcast and episode identifiers. ## OpenAPI ````yaml /openapi.json get /v1/entities/lookup openapi: 3.1.0 info: description: Public API for Particle — news intelligence, financial data, and analysis. title: Particle API version: 0.1.0 x-guidance: >- Podcast, people, company and topic intelligence. Authenticate with a pp_ API key (X-API-Key header) or pay per request with x402: a keyless call to a billable endpoint returns 402 with the payment requirements in the PAYMENT-REQUIRED header; sign the USDC transfer and repeat the request with PAYMENT-SIGNATURE. Start with GET /v1/podcasts/search?q=; the slugs in responses are the inputs to the other endpoints. Docs: https://docs.particle.pro; setup playbook: https://api.particle.pro/agents.md; endpoint and tool map with prices: https://api.particle.pro/llms.txt; credential recipe: https://api.particle.pro/auth.md. servers: - url: https://api.particle.pro security: - ApiKeyHeader: [] - BearerAuth: [] paths: /v1/entities/lookup: get: tags: - Entities - tier:standard summary: Look up people and companies by external identifier description: >- Resolves external identifiers — LinkedIn slugs, social handles, company domains, stock tickers, SEC CIKs, Wikidata QIDs — to the people and companies that carry them. It is the reverse of GET /v1/people/{slug}/external-links and GET /v1/companies/{id}/external-links. Pass a comma-separated `identifier` list (up to 100 per call); `platform` is optional, so a handle with no known source still resolves. A full profile URL works in place of a bare identifier and the platform is inferred from it, and the stored form is matched for you — pass `satyanadella` or the profile URL, not `in/satyanadella`. Each result echoes the input identifier and carries a `matches` array, because an identifier is not unique to an entity: a LinkedIn profile claimed by two duplicate person records resolves to both, and `match_count` reports the total. Unresolved identifiers come back with an empty `matches`, so a bulk caller never has to reconcile a shorter response against a longer request. Correlate by the echoed `identifier` rather than by position, since duplicate identifiers collapse to one result. Use GET /v1/entities/search instead when you have a name rather than an identifier, and GET /v1/podcasts/lookup or GET /v1/podcasts/episodes/lookup for podcast and episode identifiers. operationId: lookup-entities parameters: - description: >- One or more external identifiers to resolve. Pass a comma-separated list to look up many at once (max 100 per call). A full profile URL works in place of a bare identifier and the platform is inferred from it. The identifier is echoed back exactly as supplied, not normalized. explode: false in: query name: identifier required: true schema: description: >- One or more external identifiers to resolve. Pass a comma-separated list to look up many at once (max 100 per call). A full profile URL works in place of a bare identifier and the platform is inferred from it. The identifier is echoed back exactly as supplied, not normalized. examples: - - in/satyanadella - microsoft.com items: type: string maxItems: 100 minItems: 1 type: - array - 'null' - description: >- Restrict the lookup to one platform. Optional — omit it to match the identifier on any platform, which is what you want when you hold a handle but not its source. Accepts any platform reported on the external-links endpoints plus the company identifier namespaces 'domain', 'ticker', 'sec' (CIK) and 'wikidata' (QID). explode: false in: query name: platform schema: description: >- Restrict the lookup to one platform. Optional — omit it to match the identifier on any platform, which is what you want when you hold a handle but not its source. Accepts any platform reported on the external-links endpoints plus the company identifier namespaces 'domain', 'ticker', 'sec' (CIK) and 'wikidata' (QID). examples: - linkedin type: string - description: >- Restrict results to one kind of entity. Omit to search people and companies together. explode: false in: query name: type schema: description: >- Restrict results to one kind of entity. Omit to search people and companies together. enum: - person - company type: string responses: '200': content: application/json: schema: $ref: '#/components/schemas/EntityLookup' description: OK '402': content: application/problem+json: schema: $ref: '#/components/schemas/PlatformError' description: >- Payment Required. Read error_code. payment_required is the x402 path: either a keyless request being challenged — pay $0.01 in USDC per request (requirements in the PAYMENT-REQUIRED header) or send a pp_ API key — or a supplied payment that failed settlement (details in the PAYMENT-RESPONSE header; retry the same signature before signing a new one). See https://docs.particle.pro/x402. Any other code means the credential was accepted but does not cover this request (a plan or session gate such as premium_required or paid_plan_confirmation_required); its resolve says how to obtain access, and no payment header is sent. default: content: application/problem+json: schema: $ref: '#/components/schemas/PlatformError' description: Error x-codeSamples: - label: cURL lang: curl source: |- curl -H "X-API-Key: $PARTICLE_API_KEY" \ "https://api.particle.pro/v1/entities/lookup?identifier=in%2Fsatyanadella%2Cmicrosoft.com" components: schemas: EntityLookup: additionalProperties: false properties: results: description: >- One result per unique input identifier, in request order. Duplicate identifiers in the request collapse to a single result. items: $ref: '#/components/schemas/EntityLookupResult' type: - array - 'null' required: - results type: object PlatformError: additionalProperties: false properties: detail: description: >- A human-readable explanation specific to this occurrence of the problem. examples: - Property foo is required but is missing. type: string error_code: type: string errors: description: Optional list of individual error details items: $ref: '#/components/schemas/ErrorDetail' type: - array - 'null' instance: description: >- A URI reference that identifies the specific occurrence of the problem. examples: - https://example.com/error-log/abc123 format: uri type: string resolve: $ref: '#/components/schemas/ErrorResolve' status: description: HTTP status code examples: - 400 format: int64 type: integer title: description: >- A short, human-readable summary of the problem type. This value should not change between occurrences of the error. examples: - Bad Request type: string type: default: about:blank description: A URI reference to human-readable documentation for the error. examples: - https://example.com/errors/example format: uri type: string type: object EntityLookupResult: additionalProperties: false properties: identifier: description: The identifier exactly as supplied in the request, not normalized. type: string match_count: description: >- How many distinct entities carry this identifier. Larger than the length of 'matches' when more than 10 do. A count above 1 means the identifier is shared, usually by duplicate records for the same real person — 8.7% of LinkedIn identifiers are. format: int64 type: integer matches: description: >- The entities carrying this identifier, best first: records linked to a knowledge graph entity come before those without, then oldest first. Empty when the identifier does not resolve. items: $ref: '#/components/schemas/EntityLookupMatch' type: - array - 'null' platforms: description: >- The platforms this identifier matched on, alphabetically. Usually one. Several when a handle is the same across platforms and no 'platform' filter was given. Omitted when nothing matched. items: type: string type: - array - 'null' required: - identifier - matches - match_count type: object ErrorDetail: additionalProperties: false properties: location: description: >- Where the error occurred, e.g. 'body.items[3].tags' or 'path.thing-id' type: string message: description: Error message text type: string value: description: The value at the given location type: object ErrorResolve: additionalProperties: false properties: action: type: string endpoint: type: string message: type: string method: type: string url: type: string required: - message type: object EntityLookupMatch: additionalProperties: false properties: company: $ref: '#/components/schemas/CompanyCompact' description: The matched company. Set when type is 'company'. person: $ref: '#/components/schemas/PersonCompact' description: The matched person. Set when type is 'person'. type: description: >- Which kind of entity matched. The corresponding field below is the one that is set. enum: - person - company type: string required: - type type: object CompanyCompact: additionalProperties: false properties: description: description: Short company description, when known. type: string domain: description: Primary website domain (e.g. 'nvidia.com'), when known. type: string id: description: Company identifier (domain, slug, or encoded ID) type: string image_mode: description: >- Image presentation policy. AUTOMATIC permits client fallbacks, CUSTOM requires image_url, and NONE suppresses all image fallbacks. enum: - AUTOMATIC - CUSTOM - NONE type: string image_url: description: Company logo or image URL type: string name: description: Company name type: string slug: description: >- Stable human-readable handle (the linked knowledge-graph slug, e.g. 'nvidia'), when known. Companies have no slug of their own; prefer this for display and pass it (or id) to /v1/companies. type: string ticker: description: Primary stock ticker symbol, when listed. type: string required: - id - name type: object PersonCompact: additionalProperties: false properties: description: description: Short description (e.g. current role), when known. type: string id: description: Encoded Person identifier type: string image_url: description: Canonical headshot URL when one is known for the Person type: string name: description: Display name type: string slug: description: >- Stable human-readable handle (e.g. 'satya-nadella'). Recommended canonical identifier on every Particle Pro person surface. type: string required: - id - name type: object securitySchemes: ApiKeyHeader: description: Pass your API key in the X-API-Key header (recommended). in: header name: X-API-Key type: apiKey BearerAuth: description: Pass your API key as a Bearer token in the Authorization header. scheme: bearer type: http ````