Nationalize API reference

A simple API that estimates the nationality of a person based on a last name

The Nationalize API allows you to check the statistical probability of a name belonging to a certain nationality.

The API exposes a single endpoint that accepts a name and returns a payload with the prediction. It uses query parameters for requests and returns JSON-encoded responses.

The API is free for up to 100 names/day. No sign-up or API key is needed. So go ahead and try it out. You can sign up for an API key if you need more requests.

We support batch processing to reduce the overhead of many HTTP calls.

The API is built for high-volume processing, and as such, there is no rate limiting except your daily or monthly limit. You can keep track of that through rate-limiting headers or your account.

Client libraries

Not looking to write your own client code? Our amazing community has open sourced libraries and SDK's for almost every programming language.

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Basic Usage

Predicting the nationality of a single name

For basic usage you just need to pass a name as the name parameter. It's recommended to always use a last name if you have it available. If not, the API will attempt to parse the input as a full name and pick out the first name.

The response includes a count indicating the amount of data rows examined for the response and a country list with the top five most likely countries, each with a country_id and a probability. You can read more about our data here.

Request Try me

Accessing the API

The API is free to use for up to 100 requests/day. If you need to do more predictions than that, you can obtain an API key from the store.

You should append the key to every request using the apikey parameter.

To keep track of the number of requests you have left for a given period, you can use the following HTTP headers returned in the response. If you're using an API key, you can also check your account to keep track of your usage.


The total amount of names available in the current time window. For free usage, this will be 100 predictions and for subscriptions it will follow your tier.


The remaining amount of names available in the current time window.


Seconds remaining until a new time window open. Free usage runs on a daily window and subscriptions follow the monthly billing period.{YOUR_API_KEY}
Batch Usage

Estimating the nationality of multiple names

The API allows you to infer the gender of up to ten names per request. To do so, send a list of names as the name parameter. The response will be a list of predictions.

Each name will count as a request towards rate limiting. If you don't have enough requests left to process every name, an error will be returned.

Request[]=johnson&name[]=bakshi Try me
Input Fallbacks

How input fallbacks work

The API uses a few fallbacks to find a match in our database for cases where the input name is not directly found.

The first fallback will remove all diacritics from the input name and make an attempt to find a match without it. The second fallback will attempt to parse the name in case it's a full name and use the found last name.

So the lookup priority looks like this.

  • Direct look up of the input name

  • Look up of the input name with diacritics removed

  • Attemp to parse the name into it's parts and look up the last name

Even though we support name parsing, it's recommended to always use a last name if you have it available. Naming conventions are different across cultures and contexts and the parsing will never be perfect.

Responses & Errors

Understanding the API responses

All responses wil be in content-type: application/json, charset=utf-8.

Here's a list of possible error codes and their explanation.

Code Description Response
{ "error": "Invalid API key" }
Payment Required
{ "error": "Subscription is not active" }
Unprocessable Content
{ "error": "Missing 'name' parameter" }
Unprocessable Content
{ "error": "Invalid 'name' parameter" }
Too many requests
{ "error": "Request limit reached" }
Too many requests
{ "error": "Request limit too low to process request" }