About

Development on ipapi.is started in early 2021 because there was an internal need to accurately detect hosting provider IP ranges in order to defend against automated attacks. Detecting hosting ranges was achieved by downloading the self-published IP ranges from the major cloud providers (such as AWS or Google Cloud) and by manually labeling networks from raw WHOIS records. As the project progressed, more data fields were added to the API, such as company, asn, and location API fields.

Some advanced Proxy/VPN detection tests, such as the IP timezone vs Browser timezone mismatch test, require IP geolocation data. Therefore, IP geolocation data was added to the API. This particular test is able to detect proxies and VPNs, because such proxy/VPN clients often keep the OS or browser time settings left intact and do not match it to the timezone characteristic of the IP address.

ipapi.is was started as a research project and acted primarily as a home for various research ideas related to IP address data and IT security. When the API started to mature, more businesses started to depend on it and ipapi.is is now an established player in the IP API field. As of 2025, the API can be considered as a serious contender to other IP API services such as ipdata.co or ipinfo.io, as a recent blog post titled ipinfo.io Alternative demonstrates.

With certain data points such as IP to Company data, ipapi.is is becoming an industry leader regarding data quality, as a recent blog post titled ipinfo.io has worse data accuracy than ipapi.is proves.

ipapi.is preferably uses public data to populate the database that is used for the API. For instance, IP geolocation intelligence is obtained from publicly downloadable WHOIS records and reverse IP lookups. Another major data source is the awesome FireHol project, from which the API flags is_proxy (firehol_anonymous.netset) and is_abuser (firehol_abusers_1d.netset) are sourced (among other proprietary sources).

A goal of this project was to prove that public data alone is sufficient to source a robust IP address API. A part of the data is freely available for download on the ipapi.is GitHub page. Another goal of the ipapi.is research project is to publish the processes and mechanisms of obtaining the data used in the API.

However, publicly available data alone is not sufficient to create an extraordinary API for cybersecurity intelligence data. Therefore, there is a strong focus on creating accurate proprietary databases as the following examples illustrate:

• VPN Service Detection - The is_vpn and vpn API flags are sourced by systematically enumerating VPN exit nodes from large VPN providers such as NordVPN or ExpressVPN. Put differently, accurate data about VPN exit nodes is obtained by systematically connecting to all available VPN regions for the most well known VPN providers.
• Hosting Detection Algorithm - A proprietary algorithm to detect previously unknown hosting/cloud IP ranges was developed. This makes ipapi.is the IP API with the best hosting detection quality available.
• Network of HoneyPots - ipapi.is uses a vast network of honeypots distributed throughout the entire Internet to source the is_abuser API field. Basically a honey pot is a server that is designed to be attacked by malicious cyber actors. IP addresses that demonstrate malicious behavior are used to source the is_abuser API field.
• Large Crawling Pipeline - In order to keep the core WHOIS data up to date and to enrich existing datasets, ipapi.is needs constant scraping and crawling. Millions of requests are fired from a distributed crawling architecture each week to keep the data up to date. For example, to derive the type field of the company and asn objects, millions of company websites are crawled, and the crawled metadata is analyzed with AI technology. Currently, the ChatGPT API is used to classify the company type based on the company's website metadata.

ipapi.is provides an extensive free plan of 1,000 requests per day, but a larger request volume (more than 30k monthly requests) is only available with purchased credits. Most similar projects either have a very limited free plan or don't include ASN and WHOIS information in their basic plan. With ipapi.is, you have access to all API output regardless of the subscription plan you choose. The only difference between the free and paid plans is in the request volume.

Up to 1,000 daily API requests are free. If you have a larger API volume, please consider subscribing to a billing plan or making a one-time credit purchase. Subscriptions are cancellable at any point in time. One-time credits never expire, and you can use them at your own pace.

API Strengths

ipapi.is has several strengths:

• IP Geolocation: By parsing WHOIS data and using open-source geolocation projects, an accurate and frequently updated geolocation database is compiled. A lot of large ISP and other Internet companies also submit their IP geolocation geofeeds to our IP data corrections page. This way, we can keep the geolocation database up to date.
• Accurate Hosting Detection: A complicated hosting detection algorithm uses public WHOIS data to detect thousands of hosting and cloud providers around the globe.
• VPN Exit Node Enumeration: We constantly enumerate thousands of VPN Exit Nodes on a daily basis. This makes us one of the best VPN Detection providers on the market.
• WHOIS Data: WHOIS data is the primary data source for IP address data. Since not all possible use cases for IP address data are known, ipapi.is provides raw and updated WHOIS records for all active ASNs and IP networks.
• IP to ASN: The API provides accurate and frequently updated ASN information for all autonomous systems. If the ASN is active (at least one route assigned to it), WHOIS information is returned on top of it.
• IP to Organization: Each IP address is owned (or allocated) by a company or organization. Knowing which organization is responsible for a certain IP range helps classify traffic originating from it in a better way. Organization data is also sourced from WHOIS records.

API Accuracy

There is a strong focus on data accuracy, but since the API consumes many third-party public IP address projects, it is impossible to guarantee error-free API output in all cases. Even WHOIS data, which otherwise is the most reliable data source for IP address data, may be erroneous at times, since at times the responsible organizations make mistakes while submitting their WHOIS data points.

In case an error is found in the data, please don't hesitate to contact ipapi.is via the email: info@ipapi.is.

You may also submit an IP data correction automatically to us by visiting the IP data corrections page.

Future Project Direction and Outlook

The data quality of ipapi.is is constantly improving. The following projects are planned for the future or currently in process:

• Zero Downtime API - Unfortunately, there were some API downtimes during 2025. The simple goal is to have a very robust zero downtime API. The API status can be tracked here: https://ipapi.is/status.html
• Improve current VPN enumeration pipeline - Albeit the current VPN enumeration pipeline is not bad, it is always important to improve it and add new VPN providers to it.
• Derive IP geolocation intelligence from IPv4 Reverse DNS data - Basically, the task is to replicate most of the findings from Microsoft Research paper "IP Geolocation through Reverse DNS"
• Forward DNS Lookup of all known Domains (Not yet started) - The Internet consists of hundreds of millions domains from hundreds of TLDs. For many reasons, it is interesting to know which IP address hosts which domain name. Therefore, a complete forward DNS lookup of all known domain names is planned.

The following projects were already achieved and are completed:

• Create a stable v1 API output format - The data format of the API is mature as of 2025.
• Systematically compare ipapi.is data quality with best competitors ipinfo.io, ipqualityscore.com, ipdata.co, ipapi.com (Completed in October 2024) - The best kind of advertisement is to prove that ipapi.is data quality is superior to the main competitors. The API quality was compared to the main competitors by using a transparent and fully public test case. The results were published in the following blog articles: An honest Comparison of ipapi.is to its Competitors and IP to Company Accuracy . Another, more recent blog article from 2025 named Why ipapi.is is better than ipinfo.io shows once more that ipapi.is is an industry leader regarding IP to Company accuracy.
• Improve the organization coverage (Completed in June 2024) - The task is to improve the organizational granularity of ipapi.is as it is seen in the company output object.
• Reverse DNS Lookup of the entire IPv4 Address Space (Started in Nov 2023, completed in Jan 2024) - Reverse DNS lookups for IP addresses can help to enrich the IP geolocation quality. Furthermore, reverse DNS data can be used to determine the connection type of an IP address. For that reason, a continuous reverse DNS lookup of the entire IPv4 space was conducted. The reverse DNS querying of 3.7 Billion (!) IPv4 addresses took roughly two months. The data will be used internally for ipapi.is, but the Reverse DNS database will also be sold directly on ipapi.is.