Identify (Reverse Email Lookup)

Use this when you have a list of emails and need to know who each one belongs to, at bulk scale. Each match returns the person’s crustdata_person_id, basic profile, and profile URL. Submit a job, then poll or receive a webhook when it finishes. You pay only for the emails that resolve to a person.

Identify is enabled per account. If your plan does not include it, contact your Crustdata account team.

Identify vs Enrich. Identify answers “who is this email?”. It returns the matched person’s crustdata_person_id, basic_profile (name, headline, title), and social_handles (profile URL). If you also need contact data, full employment history, or company IDs per role, use Person Enrich (which also supports reverse lookup by business email).

How it works

Reverse identify is an asynchronous, two-call flow — you submit a job, then fetch the results once it finishes:

Submit your emails

POST /batch/person/identify with your list of emails (or professional_network_profile_urls). You get a batch_id back immediately.

Poll, or wait for a webhook

GET /batch/{batch_id} to check the job status — or pass a webhook_url on submit and we call you when it finishes.

Download the results

Once status is completed, the status response includes a download_url: a gzipped JSONL file with one record per input, valid for 5 days.

Emails already known to Crustdata resolve in seconds. Emails that require real-time retrieval take longer, which is why this endpoint is asynchronous.

Replace YOUR_API_KEY in each example with your actual API key. All requests require the x-api-version: 2025-11-01 header.

Pricing: 1 credit per email that resolves to a person — unmatched emails are free. See Pricing for details. Limits: up to 300 identifiers per submission. Active jobs are capped per account across the live endpoints (5 on default limits) - see Rate limits.

1. Submit your emails

Send your emails in emails — business or personal addresses both work. The response returns a batch_id immediately — the job runs asynchronously.

curl --request POST \
  --url https://api.crustdata.com/batch/person/identify \
  --header 'authorization: Bearer YOUR_API_KEY' \
  --header 'content-type: application/json' \
  --header 'x-api-version: 2025-11-01' \
  --data '{
    "emails": [
      "abhilash@crustdata.com",
      "ankit.harbhajanka@aequs.com"
    ]
  }'

{
    "batch_id": "f0d86a5d-0031-4ca4-b350-92162fb38850",
    "status": "pending",
    "entity": "person",
    "action": "identify",
    "identifier_count": 2,
    "entities_requested": 2,
    "status_url": "/batch/f0d86a5d-0031-4ca4-b350-92162fb38850"
}

You can submit professional_network_profile_urls instead of emails to resolve profile URLs to their crustdata_person_id. Submit exactly one identifier type per job. To be notified when the job finishes instead of polling, include a webhook_url in the request body.

2. Get the results

Poll the status_url (or GET /batch/{batch_id}). While the job runs, status is pending or processing. When it is completed, the response includes a download_url.

curl --request GET \
  --url https://api.crustdata.com/batch/f0d86a5d-0031-4ca4-b350-92162fb38850 \
  --header 'authorization: Bearer YOUR_API_KEY' \
  --header 'x-api-version: 2025-11-01'

{
    "batch_id": "f0d86a5d-0031-4ca4-b350-92162fb38850",
    "status": "completed",
    "entity": "person",
    "action": "identify",
    "identifier_count": 2,
    "result_count": 2,
    "entities_requested": 2,
    "entities_fulfilled": 2,
    "created_at": "2026-10-01T08:07:32.927392+00:00",
    "completed_at": "2026-10-01T08:07:33.582570+00:00",
    "download_url": "https://crustdata-batch-api-data.s3.amazonaws.com/f0d86a5d-0031-4ca4-b350-92162fb38850/output/results.jsonl.gz?...",
    "download_urls": [
        "https://crustdata-batch-api-data.s3.amazonaws.com/f0d86a5d-0031-4ca4-b350-92162fb38850/output/part-000.jsonl.gz?..."
    ]
}

The download_url points to gzipped JSONL (.jsonl.gz) with one record per submitted identifier. The link is valid for 5 days. download_urls lists the same data split into parts. Both links are pre-signed, and the example trims their query string to ?....

Result format

Each line is one record for an input identifier:

{
  "matched_on": "abhilash@crustdata.com",
  "match_type": "email",
  "matches": [
    {
      "confidence_score": 1.0,
      "person_data": {
        "crustdata_person_id": 1068035,
        "basic_profile": {
          "name": "Abhilash Chowdhary",
          "headline": "Co-founder at Crustdata (YC F24) | Infra for building AI employees",
          "current_title": "Co-Founder & CEO",
          "summary": "Love building things. A software engineer with vast experience in shipping products spanning robotics, web technologies and quantitative finance.",
          "languages": ["English", "Hindi"],
          "location": {
            "city": "San Francisco",
            "state": "California",
            "country": "United States",
            "continent": "North America",
            "raw": "San Francisco, California, United States",
            "full_location": null
          }
        },
        "social_handles": {
          "professional_network_identifier": {
            "profile_url": "https://www.linkedin.com/in/abhilashchowdhary",
            "urn_url": "https://www.linkedin.com/in/ACoAAAxLzxABgXUODmAZY4ZFYAxenZ10K0hTyY4"
          },
          "dev_platform_identifier": { "profile_url": null },
          "twitter_identifier": { "slug": "" }
        },
        "updated_at": "2026-09-30T11:06:14.480375Z"
      }
    }
  ]
}

A match carries the person’s profile URL in social_handles.professional_network_identifier.profile_url. Submit that URL to Person Enrich for the full profile, or to Batch Contact Enrich for emails and phone numbers. The same object holds urn_url, the permanent form of the profile URL. The profile_url can change when the person edits it. The urn_url does not change, so you can use it as a stable key for the person. The example leaves some basic_profile fields out. A match returns the same basic_profile fields that the Person Enrich reference lists. An email with no match returns an empty matches array (and is not billed):

{ "matched_on": "nobody@unknown-domain.com", "match_type": "email", "matches": [] }

Invalid emails

An invalid email does not fail the job. Its row has an empty matches array and an error_message that gives the reason:

{ "matched_on": "not-an-email", "match_type": "email", "matches": [], "error_message": "Invalid email: malformed address" }

`error_message`	When
`Invalid email: malformed address`	The address is not valid email syntax, for example it has no `@`.
`Invalid email: contains whitespace`	The address contains a space.
`Invalid email: non-ASCII characters`	The address contains a non-ASCII character, such as `é`.
`Invalid email: placeholder domain`	The domain is a placeholder, such as `example.com`.
`Invalid email: unrecognized domain`	The domain does not end in a known suffix.

You do not pay for an invalid email, and the job’s result_count leaves it out. If every email in the request is invalid, the submit returns 400 instead. See Errors.

Personal emails resolve too

Reverse lookup is not limited to business addresses — a personal email (for example a Gmail address) resolves the same way when it can be matched to a person. Submit it in emails like any other address:

curl --request POST \
  --url https://api.crustdata.com/batch/person/identify \
  --header 'authorization: Bearer YOUR_API_KEY' \
  --header 'content-type: application/json' \
  --header 'x-api-version: 2025-11-01' \
  --data '{
    "emails": ["jane.doe91@gmail.com"]
  }'

The result row has the same shape as above. Personal addresses that cannot be matched return the usual empty matches array and are not billed.

Request parameters

Parameter	Type	Required	Description
`emails`	string[]	One identifier of	Emails to reverse-lookup — business or personal addresses. Max 300 per submission. Result rows carry `match_type: "email"`.
`business_emails`	string[]	One identifier of	Emails to reverse-lookup, the same way as `emails`. Business and personal addresses both resolve. Max 300 per submission. Result rows carry `match_type: "business_email"`.
`professional_network_profile_urls`	string[]	One identifier of	Profile URLs to resolve to a `crustdata_person_id`. Max 300 per submission.
`webhook_url`	string	No	URL to call when the job finishes, instead of polling.

Submit exactly one identifier type per job: emails, business_emails, or professional_network_profile_urls. This endpoint does not accept fields. Every match returns the same sections.

Response fields

Field	Description
`matched_on`	The input value this record resolved (the email or profile URL you submitted).
`match_type`	`email`, `business_email`, or `professional_network_profile_url`. It mirrors the identifier key you submitted.
`matches`	Array of matches. Empty when nothing resolved.
`matches[].confidence_score`	Match confidence, `0`–`1`.
`matches[].person_data`	`crustdata_person_id`, `basic_profile`, `social_handles`, and `updated_at` for the matched person.
`matches[].person_data.social_handles`	The person’s profile URL, in `professional_network_identifier.profile_url`, and its permanent form, in `professional_network_identifier.urn_url`. It also holds `dev_platform_identifier.profile_url` and `twitter_identifier.slug`, which can be `null` or empty.
`error_message`	Present only on a row whose email is invalid. See Invalid emails.

Job lifecycle

Status	Meaning
`pending`	Job accepted, not yet started.
`processing`	Job is running.
`completed`	Job finished — `download_url` is available.
`failed`	Job failed. Nothing was billed.

Errors

An invalid request body returns 400 with error.type of invalid_request and one of these messages:

`error.message`	When
`Exactly one identifier must be provided: emails, professional_network_profile_urls, or business_emails`	The body has no identifier.
`Only one identifier type can be provided. Found: emails, professional_network_profile_urls`	The body has more than one identifier type.
`Maximum 300 identifiers allowed for person/identify. Found 301`	The list has more than 300 values.
`'fields' is not a valid parameter.`	The body includes `fields`.
`Invalid emails: not-an-email, jane@example.com`	Every email in the list is invalid. The message lists them.
`Invalid professional_network_profile_urls: https://example.com/jane`	A profile URL is malformed. The message lists each bad URL.

400 - no identifier

{
    "error": {
        "type": "invalid_request",
        "message": "Exactly one identifier must be provided: emails, professional_network_profile_urls, or business_emails",
        "metadata": []
    }
}

The API rejects the whole request when one profile URL is malformed. It accepts a request where only some emails are invalid. See Invalid emails. If Identify is not enabled on your account, the submit returns 403 with error.type of permission_error.

API reference summary

Detail	Value
Submit	`POST /batch/person/identify`
Poll	`GET /batch/{batch_id}`
Auth	Bearer token + `x-api-version: 2025-11-01`
Request	One of `emails`, `business_emails`, or `professional_network_profile_urls` (max 300). Optional: `webhook_url`.
Response	Submit returns `batch_id` + `status`; poll returns `status` and a `download_url` when complete.
Output	Gzipped JSONL, one record per identifier, download link valid 5 days.
Billing	1 credit per matched person; unmatched identifiers are free.
Errors	`400`, `401`, `402`, `403`, `404`, `429`, `500`

For credit pricing, see Pricing. For throughput guidance, see Rate limits.

What to do next

Need contact data? Use Contact Enrich.
Need full employment history? Use Person Enrich with the profile_url from the match.
Enrich contact info in bulk — Batch Contact Enrich returns emails and phone numbers for a list of profile URLs.
Find people first — use Person Search to build the list to identify.

​How it works

​1. Submit your emails

​2. Get the results

​Result format

​Invalid emails

​Personal emails resolve too

​Request parameters

​Response fields

​Job lifecycle

​Errors

​API reference summary

​What to do next

How it works

1. Submit your emails

2. Get the results

Result format

Invalid emails

Personal emails resolve too

Request parameters

Response fields

Job lifecycle

Errors

API reference summary

What to do next