I pull GeoIP data into a PostgreSQL database and do the lookups from there. Here's my writeup from 2018 (the software still works fine on my system, no guarantees though): GeoIP revisited

PostgreSQL is nice for this, since it supports CIDR address ranges, you can do stuff like this:

SELECT country_code, city_name, latitude, longitude, radius FROM geoip WHERE ? << netblock LIMIT 1

With the proper GIST index, it works reasonably fast, too.

CREATE INDEX geoip_netblock_idx ON geoip USING GIST(netblock inet_ops);

Cables_DB=# SELECT country_code, city_name, latitude, longitude, radiu
+s FROM geoip WHERE '8.8.8.8' << netblock LIMIT 1;
 country_code | city_name | latitude | longitude | radius 
--------------+-----------+----------+-----------+--------
 US           |           |   37.751 |   -97.822 |   1000
(1 row)

Cables_DB=# EXPLAIN SELECT country_code, city_name, latitude, longitud
+e, radius FROM geoip WHERE '8.8.8.8' << netblock LIMIT 1;
                                      QUERY PLAN                      
+                 
----------------------------------------------------------------------
+-----------------
 Limit  (cost=0.41..8.43 rows=1 width=35)
   ->  Index Scan using geoip_netblock_idx on geoip  (cost=0.41..8.43 
+rows=1 width=35)
         Index Cond: ((netblock)::inet >> '8.8.8.8'::inet)
(3 rows)
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