Email Finder API (V2)

Email Finder API allows you to search for new business email addresses using our proprietary technologies.

The Email Finder API uses a person’s first and last name and a domain or company name to test a variety of patterns and combinations in real time until it identifies a valid business email. It does not use or process customer data at any point to aid in this search.

Privacy and Security Note – Email Finder API searches are performed in real time and do not use stored or processed customer data. Customer privacy and security are and will always remain our top priority.

How to use the Email Finder API

Before you begin, ensure that your account has enough credits or subscription queries. A successful Email Finder API search will consume one (1) subscription query or 20 credits.

We deduct zero credits or queries if a response is undetermined.

To use the Email Finder API, use the following URL, method, and parameters. Be sure to review the successful response example below and the response details to ensure your API configuration works correctly.

API DEFAULT URL https://api.zerobounce.net/v2/guessformat

API U.S.A. URL*: https://api-us.zerobounce.net/v2/guessformat

API EU URL: https://api-eu.zerobounce.net/v2/guessformat

Method: GET or POST

Starting September 3, 2026, this endpoint also accepts POST. Use the same parameters as GET, sent in the request body as application/x-www-form-urlencoded.

*This endpoint uses servers located within the United States. By utilizing this endpoint, you acknowledge and consent to your data being processed on servers in the United States.

Parameter
Required
Description

api_key
Yes
Your API Key, found in your account.
domain
Yes
The email domain for which to find the email format.
company_name
Yes
The company name for which to find the email format.
first_name
No
The first name of the person whose email format is being searched. [optional]
middle_name
No
The middle name of the person whose email format is being searched. [optional]
last_name
No
The last name of the person whose email format is being searched. [optional]

Note: Either the “domain” or the “company_name” must be entered.

Successful Response

Response Details

Properties
Description

email
The resulting email address identified by the API.
email_confidence
The level of confidence we have that the email exists. Possible values: HIGH, MEDIUM, LOW.
domain
The provided domain name.
company_name
The company associated with the domain.
did_you_mean
e.g. a suggestion in case case a firstname is used in the lastname field
failure_reason
A reason for the unknown result. Possible values can be found in the "Possible reasons for unknown status" section below.

Possible failure reasons for unknown status

Properties
Description

FREE_DOMAIN_ERROR
Cannot find pattern for free domains
DOMAIN_SYNTAX_ERROR
Domain syntax error
COMPANY_DOMAIN_ERROR
Either the domain or the company name must be entered
COMPANY_DOMAIN_NOT_FOUND
There is no domain assigned for this company name
UNEXPECTED_ERROR_OCCURRED_DURING_VALIDATION
Unexpected error occurred during validation
DOMAIN_DOES_NOT_ACCEPT_MAIL
Domain does not accept mail
NO_DATA_FOR_THIS_DOMAIN
No data for this domain
NO_DATA_FOR_THIS_COMPANY
No data for this company

Other potential error messages

You can resolve this error by ensuring that there is at least one (1) subscription query or 20 ZeroBounce credits in your account balance before making your next API call. Additionally, ensure that the API key is valid.

Email Finder API confidence levels

For each email address format that the Email Finder API generates, we assign a corresponding confidence level to indicate the probability that the address is actively in use on the respective email domain.

The confidence levels are listed below:

LOW - unlikely to be in use; high-risk
MEDIUM - medium level of confidence; the format may be in use
HIGH - highest level of confidence, format likely in use based on validation results

The Email Finder API lets you reliably identify business email addresses for your potential leads or business contacts.

If you need further assistance configuring the Email Finder API or need help to understand your results, the ZeroBounce customer support team is available 24/7.