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FastAppend API Documentation

Welcome to the FastAppend API. This RESTful API allows you to programmatically enrich your contact data with our comprehensive data enrichment services.

Base URL

https://app.fastappend.com/v1/api/

Available Services

Business Trace

Enrich business names with complete contact information including addresses, phone numbers, and emails.

Email Append

Reverse lookup email addresses to find associated contact information and additional email addresses.

Phone Append

Reverse lookup phone numbers to discover owner information and related contact details.

Name Append

Search for individuals by name and location to find their contact information.

API Access

Included With Every Account

Every FastAppend account includes API access. You can find your API key in Profile Settings and use it with any of our API endpoints.

Authentication

All API requests require authentication using a Bearer token in the Authorization header.

Authorization: Bearer <YOUR_API_KEY>

Sign in to FastAppend, open Profile Settings, and copy your API token. Treat it like a password and do not include it in shared code or public repositories.

Create Business Trace Job

POST

Upload a CSV file with business names and states to enrich with business addresses, contact persons, phone numbers, and email addresses. The completed CSV includes DNC, TCPA, state DNC, and contactable fields for every returned phone.

POST /v1/api/business-trace/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
multipart/form-data

Parameters

Name
Location
Type
Required
Description
csv_file
form-data
file
Yes
CSV file containing business names and states
business_name_column
form-data
string
Yes
Name of the column containing business names
state_column
form-data
string
Yes
Name of the column containing state abbreviations (e.g., TX, CA)

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/business-trace/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -F 'csv_file=@/path/to/businesses.csv' \
  -F 'business_name_column=business_name' \
  -F 'state_column=state'

Response (201)

{
  "queue_id": 123,
  "status": "pending",
  "service_type": "business trace",
  "created_at": "2025-01-04T10:30:00Z",
  "message": "Business trace job created successfully"
}

Get Business Trace Job Status

GET

Retrieve the processing status and complete result CSV for a business trace job. Phone compliance fields are included directly in the result CSV.

GET /v1/api/business-trace/<queue_id>/

Headers

Authorization
Bearer <YOUR_API_KEY>

Parameters

Name
Location
Type
Required
Description
queue_id
path
integer
Yes
The queue ID returned when creating the job

Example Request

curl -X GET 'https://app.fastappend.com/v1/api/business-trace/123/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>'

Response (200)

{
  "id": 123,
  "created_at": "2025-01-04T10:30:00Z",
  "pending": false,
  "service_type": "business trace",
  "download_url": "https://fastappend.nyc3.cdn.digitaloceanspaces.com/fastappend/processed_file.csv",
  "phones_checked": 850,
  "phones_flagged": 210,
  "rows_uploaded": 500,
  "credits_deducted": 450
}

Synchronous Business Trace

POST

Look up one business by name and state and receive business addresses plus up to five associated people with ranked phones, emails, and role context. Results return synchronously without a CSV queue. A successful hit costs 1 business credit; misses are not charged. Rate limit: 500 requests per minute.

POST /v1/api/business-trace/lookup/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
application/json

Parameters

Name
Location
Type
Required
Description
company_name
body
string
Yes
The business name to look up (e.g., "Elume Electrical Inc")
state
body
string
Yes
State abbreviation or full name (e.g., "CA" or "California")

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/business-trace/lookup/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{
    "company_name": "Acme Construction LLC",
    "state": "CA"
  }'

Response (200)

{
  "company_name": "Acme Construction LLC",
  "state": "CA",
  "addresses": [
    {
      "street": "1234 Main Street",
      "city": "Los Angeles",
      "state": "CA",
      "zip": "90001"
    }
  ],
  "associated_people_count": 1,
  "associated_people": [
    {
      "first_name": "Jane",
      "middle_name": "",
      "last_name": "Doe",
      "full_name": "Jane Doe",
      "age": 46,
      "dob": "10-1980",
      "deceased": false,
      "litigator": false,
      "mailing_address": {
        "street": "5678 Oak Avenue",
        "city": "Pasadena",
        "state": "CA",
        "zip": "91101"
      },
      "phones": [
        {
          "number": "3105550100",
          "is_input": false,
          "type": "Mobile",
          "dnc": false,
          "tcpa": false,
          "state_dnc": [],
          "contactable": true,
          "carrier": "Example Wireless",
          "last_seen": "2026-08-01",
          "rank": 1
        }
      ],
      "emails": [
        {
          "email": "[email protected]",
          "is_input": false,
          "rank": 1
        }
      ],
      "rank": 1,
      "role": "Manager",
      "is_registered_agent": false
    }
  ],
  "hit": true,
  "credits_deducted": 2,
  "meta": {
    "request_id": "req_b0e2ba54941820e3009e83c0cd14dda6",
    "timestamp": "2026-08-20T20:00:00Z",
    "api_version": "2026-08-20"
  }
}

Create Email Append Job

POST

Upload a CSV file with email addresses to append names, phone numbers, addresses, and related emails. The completed CSV includes DNC, TCPA, state DNC, and contactable fields for every returned phone.

POST /v1/api/email-append/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
multipart/form-data

Parameters

Name
Location
Type
Required
Description
csv_file
form-data
file
Yes
CSV file containing email addresses
email_column
form-data
string
Yes
Name of the column containing email addresses

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/email-append/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -F 'csv_file=@/path/to/emails.csv' \
  -F 'email_column=email'

Response (201)

{
  "queue_id": 456,
  "status": "pending",
  "service_type": "email append",
  "created_at": "2025-01-04T11:00:00Z",
  "message": "Email append job created successfully"
}

Get Email Append Job Status

GET

Retrieve the processing status and complete result CSV for an email append job. Phone compliance fields are included directly in the result CSV.

GET /v1/api/email-append/<queue_id>/

Headers

Authorization
Bearer <YOUR_API_KEY>

Parameters

Name
Location
Type
Required
Description
queue_id
path
integer
Yes
The queue ID returned when creating the job

Example Request

curl -X GET 'https://app.fastappend.com/v1/api/email-append/456/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>'

Response (200)

{
  "id": 456,
  "created_at": "2025-01-04T11:00:00Z",
  "pending": false,
  "service_type": "email append",
  "download_url": "https://fastappend.nyc3.cdn.digitaloceanspaces.com/fastappend/processed_emails.csv",
  "phones_checked": 1200,
  "phones_flagged": 320,
  "rows_uploaded": 1000,
  "credits_deducted": 850
}

Create Phone Append Job

POST

Upload a CSV file with phone numbers to append associated names, addresses, emails, and additional phone numbers. The completed CSV includes DNC, TCPA, state DNC, and contactable fields for every returned phone.

POST /v1/api/phone-append/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
multipart/form-data

Parameters

Name
Location
Type
Required
Description
csv_file
form-data
file
Yes
CSV file containing phone numbers
phone_column
form-data
string
Yes
Name of the column containing phone numbers

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/phone-append/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -F 'csv_file=@/path/to/phones.csv' \
  -F 'phone_column=phone'

Response (201)

{
  "queue_id": 789,
  "status": "pending",
  "service_type": "phone append",
  "created_at": "2025-01-04T12:00:00Z",
  "message": "Phone append job created successfully"
}

Get Phone Append Job Status

GET

Retrieve the processing status and complete result CSV for a phone append job. Phone compliance fields are included directly in the result CSV.

GET /v1/api/phone-append/<queue_id>/

Headers

Authorization
Bearer <YOUR_API_KEY>

Parameters

Name
Location
Type
Required
Description
queue_id
path
integer
Yes
The queue ID returned when creating the job

Example Request

curl -X GET 'https://app.fastappend.com/v1/api/phone-append/789/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>'

Response (200)

{
  "id": 789,
  "created_at": "2025-01-04T12:00:00Z",
  "pending": false,
  "service_type": "phone append",
  "download_url": "https://fastappend.nyc3.cdn.digitaloceanspaces.com/fastappend/processed_phones.csv",
  "phones_checked": 1400,
  "phones_flagged": 360,
  "rows_uploaded": 750,
  "credits_deducted": 680
}

Create Name Append Job

POST

Upload a CSV file with names and location to append addresses, phone numbers, and email addresses. The completed CSV includes DNC, TCPA, state DNC, and contactable fields for every returned phone.

POST /v1/api/name-append/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
multipart/form-data

Parameters

Name
Location
Type
Required
Description
csv_file
form-data
file
Yes
CSV file containing names
first_name_column
form-data
string
Yes
Name of the column containing first names
last_name_column
form-data
string
Yes
Name of the column containing last names
middle_name_column
form-data
string
No
Name of the column containing middle names (optional, improves accuracy)
mail_city_column
form-data
string
No
Name of the column containing city (optional, improves accuracy)
mail_state_column
form-data
string
No
Name of the column containing state (optional, improves accuracy)

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/name-append/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -F 'csv_file=@/path/to/names.csv' \
  -F 'first_name_column=first_name' \
  -F 'last_name_column=last_name' \
  -F 'mail_city_column=city' \
  -F 'mail_state_column=state'

Response (201)

{
  "queue_id": 101,
  "status": "pending",
  "service_type": "name append",
  "created_at": "2025-01-04T13:00:00Z",
  "message": "Name append job created successfully"
}

Get Name Append Job Status

GET

Retrieve the processing status and complete result CSV for a name append job. Phone compliance fields are included directly in the result CSV.

GET /v1/api/name-append/<queue_id>/

Headers

Authorization
Bearer <YOUR_API_KEY>

Parameters

Name
Location
Type
Required
Description
queue_id
path
integer
Yes
The queue ID returned when creating the job

Example Request

curl -X GET 'https://app.fastappend.com/v1/api/name-append/101/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>'

Response (200)

{
  "id": 101,
  "created_at": "2025-01-04T13:00:00Z",
  "pending": false,
  "service_type": "name append",
  "download_url": "https://fastappend.nyc3.cdn.digitaloceanspaces.com/fastappend/processed_names.csv",
  "phones_checked": 510,
  "phones_flagged": 120,
  "rows_uploaded": 300,
  "credits_deducted": 270
}

Reverse Phone Append Lookup

POST

Submit one U.S. phone number and receive up to five matched people with contact details and up to three linked addresses per person. Every returned phone includes DNC, TCPA, state DNC, and contactable fields. A successful hit costs 2 appending credits; misses are not charged.

POST /v1/api/reverse-phone-append/lookup/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
application/json

Parameters

Name
Location
Type
Required
Description
phone
body
string
Yes
A 10-digit U.S. phone number

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/reverse-phone-append/lookup/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{"phone": "5125550100"}'

Response (200)

{
  "input_phone": "5125550100",
  "hit": true,
  "matched_people_count": 1,
  "credits_deducted": 2,
  "matched_people": [
    {
      "first_name": "Jane",
      "middle_name": "A",
      "last_name": "Doe",
      "full_name": "Jane A Doe",
      "age": 46,
      "dob": "10-1980",
      "deceased": false,
      "litigator": false,
      "mailing_address": {
        "street": "123 Main St",
        "city": "Austin",
        "state": "TX",
        "zip": "78701"
      },
      "linked_addresses": [
        {
          "street": "456 Oak Ave",
          "city": "Dallas",
          "state": "TX",
          "zip": "75201",
          "rank": 1
        }
      ],
      "phones": [
        {
          "number": "5125550100",
          "is_input": true,
          "type": "Mobile",
          "dnc": false,
          "tcpa": false,
          "state_dnc": [],
          "contactable": true,
          "carrier": "Example Wireless",
          "last_seen": "2026-08-01",
          "rank": 1
        }
      ],
      "emails": [
        {
          "email": "[email protected]",
          "is_input": false,
          "rank": 1
        }
      ],
      "rank": 1,
      "matched_on": {
        "phone": "5125550100"
      }
    }
  ],
  "meta": {
    "request_id": "req_0123456789abcdef",
    "timestamp": "2026-08-20T20:00:00Z",
    "api_version": "2026-08-20"
  }
}

Reverse Email Append Lookup

POST

Submit one email address and receive up to five matched people with phones, emails, and up to three linked addresses per person. Every returned phone includes DNC fields. A successful hit costs 2 appending credits; misses are not charged.

POST /v1/api/reverse-email-append/lookup/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
application/json

Parameters

Name
Location
Type
Required
Description
email
body
string
Yes
The email address to look up

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/reverse-email-append/lookup/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{"email": "[email protected]"}'

Response (200)

{
  "input_email": "[email protected]",
  "hit": true,
  "matched_people_count": 1,
  "credits_deducted": 2,
  "matched_people": [
    {
      "first_name": "Jane",
      "middle_name": "A",
      "last_name": "Doe",
      "full_name": "Jane A Doe",
      "age": 46,
      "dob": "10-1980",
      "deceased": false,
      "litigator": false,
      "mailing_address": {
        "street": "123 Main St",
        "city": "Austin",
        "state": "TX",
        "zip": "78701"
      },
      "linked_addresses": [
        {
          "street": "456 Oak Ave",
          "city": "Dallas",
          "state": "TX",
          "zip": "75201",
          "rank": 1
        }
      ],
      "phones": [
        {
          "number": "5125550100",
          "is_input": true,
          "type": "Mobile",
          "dnc": false,
          "tcpa": false,
          "state_dnc": [],
          "contactable": true,
          "carrier": "Example Wireless",
          "last_seen": "2026-08-01",
          "rank": 1
        }
      ],
      "emails": [
        {
          "email": "[email protected]",
          "is_input": false,
          "rank": 1
        }
      ],
      "rank": 1,
      "matched_on": {
        "email": "[email protected]"
      }
    }
  ],
  "meta": {
    "request_id": "req_0123456789abcdef",
    "timestamp": "2026-08-20T20:00:00Z",
    "api_version": "2026-08-20"
  }
}

Reverse Name Append Lookup

POST

Submit a person name with city and state and receive up to five location-matched people with phones, emails, and up to three linked addresses per person. Every returned phone includes DNC fields. A successful hit costs 2 appending credits; misses are not charged.

POST /v1/api/reverse-name-append/lookup/

Headers

Authorization
Bearer <YOUR_API_KEY>
Content-Type
application/json

Parameters

Name
Location
Type
Required
Description
first_name
body
string
Yes
First name
middle_name
body
string
No
Middle name
last_name
body
string
Yes
Last name
city
body
string
Yes
City
state
body
string
Yes
State abbreviation or full name

Example Request

curl -X POST 'https://app.fastappend.com/v1/api/reverse-name-append/lookup/' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{"first_name": "Jane", "last_name": "Doe", "city": "Austin", "state": "TX"}'

Response (200)

{
  "input_name": {
    "first_name": "Jane",
    "middle_name": "",
    "last_name": "Doe",
    "city": "Austin",
    "state": "TX"
  },
  "hit": true,
  "matched_people_count": 1,
  "credits_deducted": 2,
  "matched_people": [
    {
      "first_name": "Jane",
      "middle_name": "A",
      "last_name": "Doe",
      "full_name": "Jane A Doe",
      "age": 46,
      "dob": "10-1980",
      "deceased": false,
      "litigator": false,
      "mailing_address": {
        "street": "123 Main St",
        "city": "Austin",
        "state": "TX",
        "zip": "78701"
      },
      "linked_addresses": [
        {
          "street": "456 Oak Ave",
          "city": "Dallas",
          "state": "TX",
          "zip": "75201",
          "rank": 1
        }
      ],
      "phones": [
        {
          "number": "5125550100",
          "is_input": true,
          "type": "Mobile",
          "dnc": false,
          "tcpa": false,
          "state_dnc": [],
          "contactable": true,
          "carrier": "Example Wireless",
          "last_seen": "2026-08-01",
          "rank": 1
        }
      ],
      "emails": [
        {
          "email": "[email protected]",
          "is_input": false,
          "rank": 1
        }
      ],
      "rank": 1,
      "matched_on": {
        "first_name": "Jane",
        "middle_name": "",
        "last_name": "Doe",
        "city": "Austin",
        "state": "TX"
      }
    }
  ],
  "meta": {
    "request_id": "req_0123456789abcdef",
    "timestamp": "2026-08-20T20:00:00Z",
    "api_version": "2026-08-20"
  }
}

Webhooks

POST

FastAppend can automatically notify your application when a job completes by sending a POST request to your configured webhook URL. Configure your webhook URL in your account profile settings.

How It Works

When a queue processing job completes, FastAppend will send a POST request to the webhook URL configured in your account. No webhook registration endpoint is required - simply add your webhook URL in your profile settings.

Configuration: Set your webhook URL in your account profile settings.

Trigger: Webhooks are sent automatically when any job (Business Trace, Email Append, Phone Append, or Name Append) completes processing.

POST <YOUR_WEBHOOK_URL>

Webhook Payload

Field
Type
Description
id
integer
The queue/job ID
created_at
string
ISO 8601 timestamp when the job was created
pending
boolean
Processing status (false when complete)
type
string
Service type: "business trace", "email append", "phone append", or "name append"
download_url
string
URL to download the processed CSV file
phones_checked
integer
Number of returned phones with compliance fields in the result CSV
phones_flagged
integer
Number of returned phones with a DNC, TCPA, or state DNC flag

Example Webhook Payload

# FastAppend will POST to your webhook URL automatically
# Example of what you'll receive:
POST https://your-domain.com/webhook
Content-Type: application/json

{
  "id": 123,
  "created_at": "2025-01-04T10:30:00Z",
  "pending": false,
  "type": "business trace",
  "download_url": "https://fastappend.nyc3.cdn.digitaloceanspaces.com/fastappend/processed_file.csv",
  "phones_checked": 850,
  "phones_flagged": 210
}

Payload Data

{
  "id": 123,
  "created_at": "2025-01-04T10:30:00Z",
  "pending": false,
  "type": "business trace",
  "download_url": "https://fastappend.nyc3.cdn.digitaloceanspaces.com/fastappend/processed_file.csv",
  "phones_checked": 850,
  "phones_flagged": 210
}

Important Notes

Your webhook endpoint should return a 2xx status code to acknowledge receipt. FastAppend will timeout after 5 seconds if no response is received.

FastAppend expects your webhook endpoint to be publicly accessible and respond within 5 seconds.

For security, consider validating webhook requests by checking the queue ID against your records or implementing webhook signatures.