diff --git a/src/Config.zig b/src/Config.zig
index 675b24d..a7bdfa3 100644
--- a/src/Config.zig
+++ b/src/Config.zig
@@ -2,13 +2,19 @@ const std = @import("std");
 
 const Config = @This();
 
+pub const GeoIpFallback = enum {
+    ipwhois,
+    ip2location,
+};
+
 listen_host: []const u8,
 listen_port: u16,
 cache_size: usize,
 cache_dir: []const u8,
 
 /// GeoLite2 is used for GeoIP (IP -> geographic location)
-/// IP2Location is a fallback if IP is not found in this db
+/// When GeoLite2 data is missing or low-confidence, the configured
+/// fallback provider is used (ipwho.is by default, or IP2Location)
 geolite_path: []const u8,
 
 /// Geocache file stores location lookups
@@ -16,11 +22,18 @@ geolite_path: []const u8,
 /// a web service from Nominatum (https://nominatim.org/) is used
 geocache_file: ?[]const u8,
 
+/// Which online service to use as a fallback when GeoLite2 has no data.
+/// Default: ipwhois (ipwho.is). Alternative: ip2location (ip2location.io)
+geoip_fallback: GeoIpFallback,
+
 /// If provided, when GeoLite2 is missing data, https://www.ip2location.com/
 /// can be used. This will also be cached in the cached file
 ip2location_api_key: ?[]const u8,
 ip2location_cache_file: []const u8,
 
+/// Cache file for ipwho.is lookups
+ipwhois_cache_file: []const u8,
+
 pub fn load(allocator: std.mem.Allocator) !Config {
     var env = try std.process.getEnvMap(allocator);
     defer env.deinit();
@@ -54,6 +67,12 @@ pub fn load(allocator: std.mem.Allocator) !Config {
             });
         },
         .geocache_file = if (env.get("WTTR_GEOCACHE_FILE")) |v| try allocator.dupe(u8, v) else try std.fs.path.join(allocator, &[_][]const u8{ default_cache_dir, "geocache.json" }),
+        .geoip_fallback = blk: {
+            if (env.get("WTTR_GEOIP_FALLBACK")) |v| {
+                if (std.mem.eql(u8, v, "ip2location")) break :blk .ip2location;
+            }
+            break :blk .ipwhois;
+        },
         .ip2location_api_key = if (env.get("IP2LOCATION_API_KEY")) |v| try allocator.dupe(u8, v) else null,
         .ip2location_cache_file = blk: {
             if (env.get("IP2LOCATION_CACHE_FILE")) |v| {
@@ -61,6 +80,12 @@ pub fn load(allocator: std.mem.Allocator) !Config {
             }
             break :blk try std.fmt.allocPrint(allocator, "{s}/ip2location.cache", .{env.get("WTTR_CACHE_DIR") orelse default_cache_dir});
         },
+        .ipwhois_cache_file = blk: {
+            if (env.get("IPWHOIS_CACHE_FILE")) |v| {
+                break :blk try allocator.dupe(u8, v);
+            }
+            break :blk try std.fmt.allocPrint(allocator, "{s}/ipwhois.cache", .{env.get("WTTR_CACHE_DIR") orelse default_cache_dir});
+        },
     };
 }
 
@@ -71,6 +96,7 @@ pub fn deinit(self: Config, allocator: std.mem.Allocator) void {
     if (self.geocache_file) |f| allocator.free(f);
     if (self.ip2location_api_key) |k| allocator.free(k);
     allocator.free(self.ip2location_cache_file);
+    allocator.free(self.ipwhois_cache_file);
 }
 
 test "config loads defaults" {
diff --git a/src/http/Server.zig b/src/http/Server.zig
index e6e6ec1..e8264d2 100644
--- a/src/http/Server.zig
+++ b/src/http/Server.zig
@@ -143,7 +143,7 @@ pub const MockHarness = struct {
 
         const geoip = try allocator.create(GeoIp);
         errdefer allocator.destroy(geoip);
-        geoip.* = GeoIp.init(allocator, config.geolite_path, null, config.ip2location_cache_file) catch
+        geoip.* = GeoIp.init(allocator, config.geolite_path, config) catch
             return error.SkipZigTest;
         errdefer geoip.deinit();
 
diff --git a/src/location/GeoIp.zig b/src/location/GeoIp.zig
index f7f73ec..d1bef6a 100644
--- a/src/location/GeoIp.zig
+++ b/src/location/GeoIp.zig
@@ -1,6 +1,8 @@
 const std = @import("std");
 const Ip2location = @import("Ip2location.zig");
+const IpWhoIs = @import("IpWhoIs.zig");
 const Location = @import("resolver.zig").Location;
+const Config = @import("../Config.zig");
 
 const c = @cImport({
     @cInclude("maxminddb.h");
@@ -9,11 +11,36 @@ const c = @cImport({
 const GeoIP = @This();
 const log = std.log.scoped(.geoip);
 
+const FallbackClient = union(enum) {
+    ip2location: *Ip2location,
+    ipwhois: *IpWhoIs,
+
+    fn lookup(self: FallbackClient, ip: []const u8) ?Location {
+        return switch (self) {
+            .ip2location => |client| client.lookup(ip),
+            .ipwhois => |client| client.lookup(ip),
+        };
+    }
+
+    fn deinit(self: FallbackClient, allocator: std.mem.Allocator) void {
+        switch (self) {
+            .ip2location => |client| {
+                client.deinit();
+                allocator.destroy(client);
+            },
+            .ipwhois => |client| {
+                client.deinit();
+                allocator.destroy(client);
+            },
+        }
+    }
+};
+
 mmdb: *c.MMDB_s,
-ip2location_client: *Ip2location,
+fallback_client: FallbackClient,
 allocator: std.mem.Allocator,
 
-pub fn init(allocator: std.mem.Allocator, db_path: []const u8, api_key: ?[]const u8, cache_path: []const u8) !GeoIP {
+pub fn init(allocator: std.mem.Allocator, db_path: []const u8, config: Config) !GeoIP {
     const path_z = try std.heap.c_allocator.dupeZ(u8, db_path);
     defer std.heap.c_allocator.free(path_z);
 
@@ -24,22 +51,29 @@ pub fn init(allocator: std.mem.Allocator, db_path: []const u8, api_key: ?[]const
     if (status != c.MMDB_SUCCESS)
         return error.CannotOpenDatabase;
 
-    const client: *Ip2location = try allocator.create(Ip2location);
-    errdefer allocator.destroy(client);
-    client.* = try Ip2location.init(allocator, api_key, cache_path);
-    errdefer {
-        client.deinit();
-        allocator.destroy(client);
-    }
-
-    std.log.info(
-        "IP2Location fallback: {s} (cache: {s})",
-        .{ if (api_key) |_| "key provided, 50k/mo limit" else "no key, 1k/day limit", cache_path },
-    );
+    const fallback_client: FallbackClient = switch (config.geoip_fallback) {
+        .ip2location => blk: {
+            const client = try allocator.create(Ip2location);
+            errdefer allocator.destroy(client);
+            client.* = try Ip2location.init(allocator, config.ip2location_api_key, config.ip2location_cache_file);
+            std.log.info(
+                "GeoIP fallback: IP2Location ({s}, cache: {s})",
+                .{ if (config.ip2location_api_key) |_| "key provided, 50k/mo limit" else "no key, 1k/day limit", config.ip2location_cache_file },
+            );
+            break :blk .{ .ip2location = client };
+        },
+        .ipwhois => blk: {
+            const client = try allocator.create(IpWhoIs);
+            errdefer allocator.destroy(client);
+            client.* = try IpWhoIs.init(allocator, config.ipwhois_cache_file);
+            std.log.info("GeoIP fallback: ipwho.is (cache: {s})", .{config.ipwhois_cache_file});
+            break :blk .{ .ipwhois = client };
+        },
+    };
 
     return GeoIP{
         .mmdb = mmdb,
-        .ip2location_client = client,
+        .fallback_client = fallback_client,
         .allocator = allocator,
     };
 }
@@ -47,8 +81,7 @@ pub fn init(allocator: std.mem.Allocator, db_path: []const u8, api_key: ?[]const
 pub fn deinit(self: *GeoIP) void {
     c.MMDB_close(self.mmdb);
     self.allocator.destroy(self.mmdb);
-    self.ip2location_client.deinit();
-    self.allocator.destroy(self.ip2location_client);
+    self.fallback_client.deinit(self.allocator);
 }
 
 pub fn lookup(self: *GeoIP, ip: []const u8) ?Location {
@@ -60,8 +93,8 @@ pub fn lookup(self: *GeoIP, ip: []const u8) ?Location {
         if (self.extractCoordinates(ip, result)) |coords|
             return coords;
 
-    // Fallback to IP2Location
-    return self.ip2location_client.lookup(ip);
+    // Fallback to configured online provider
+    return self.fallback_client.lookup(ip);
 }
 
 fn lookupInternal(mmdb: *c.MMDB_s, ip: []const u8) !c.MMDB_lookup_result_s {
@@ -196,13 +229,14 @@ test "MMDB functions are callable" {
 }
 
 test "GeoIP init with invalid path fails" {
-    const result = GeoIP.init(std.testing.allocator, "/nonexistent/path.mmdb", null, "");
+    const config = try Config.load(std.testing.allocator);
+    defer config.deinit(std.testing.allocator);
+    const result = GeoIP.init(std.testing.allocator, "/nonexistent/path.mmdb", config);
     try std.testing.expectError(error.CannotOpenDatabase, result);
 }
 
 test "isUSIp detects US IPs" {
     const allocator = std.testing.allocator;
-    const Config = @import("../Config.zig");
     const config = try Config.load(allocator);
     defer config.deinit(allocator);
     const build_options = @import("build_options");
@@ -213,7 +247,7 @@ test "isUSIp detects US IPs" {
         try GeoLite2.ensureDatabase(std.testing.allocator, db_path);
     }
 
-    var geoip = GeoIP.init(std.testing.allocator, db_path, null, config.ip2location_cache_file) catch
+    var geoip = GeoIP.init(std.testing.allocator, db_path, config) catch
         return error.SkipZigTest;
     defer geoip.deinit();
 
@@ -226,7 +260,6 @@ test "isUSIp detects US IPs" {
 }
 test "lookup works" {
     const allocator = std.testing.allocator;
-    const Config = @import("../Config.zig");
     const config = try Config.load(allocator);
     defer config.deinit(allocator);
     const build_options = @import("build_options");
@@ -237,7 +270,7 @@ test "lookup works" {
         try GeoLite2.ensureDatabase(std.testing.allocator, db_path);
     }
 
-    var geoip = GeoIP.init(std.testing.allocator, db_path, null, config.ip2location_cache_file) catch
+    var geoip = GeoIP.init(std.testing.allocator, db_path, config) catch
         return error.SkipZigTest;
     defer geoip.deinit();
 
diff --git a/src/location/IpWhoIs.zig b/src/location/IpWhoIs.zig
new file mode 100644
index 0000000..8c51c6a
--- /dev/null
+++ b/src/location/IpWhoIs.zig
@@ -0,0 +1,150 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const Location = @import("resolver.zig").Location;
+const Cache = @import("Ip2location.zig").Cache;
+
+const Self = @This();
+
+const log = std.log.scoped(.ipwhois);
+
+allocator: Allocator,
+http_client: std.http.Client,
+cache: *Cache,
+
+pub fn init(allocator: Allocator, cache_path: []const u8) !Self {
+    const cache = try allocator.create(Cache);
+    errdefer allocator.destroy(cache);
+    cache.* = try .init(allocator, cache_path);
+    return .{
+        .allocator = allocator,
+        .http_client = std.http.Client{ .allocator = allocator },
+        .cache = cache,
+    };
+}
+
+pub fn deinit(self: *Self) void {
+    self.cache.deinit();
+    self.allocator.destroy(self.cache);
+    self.http_client.deinit();
+}
+
+pub fn lookup(self: *Self, ip_str: []const u8) ?Location {
+    // Parse IP to u128 for cache lookup
+    const addr = std.net.Address.parseIp(ip_str, 0) catch return null;
+    const ip_u128: u128 = switch (addr.any.family) {
+        std.posix.AF.INET => @as(u128, @intCast(std.mem.readInt(u32, @ptrCast(&addr.in.sa.addr), .big))),
+        std.posix.AF.INET6 => std.mem.readInt(u128, @ptrCast(&addr.in6.sa.addr), .big),
+        else => return null,
+    };
+    const family: u8 = if (addr.any.family == std.posix.AF.INET) 4 else 6;
+
+    // Check cache first
+    if (self.cache.get(ip_u128)) |result|
+        return result;
+
+    // Fetch from API
+    const result = self.fetch(ip_str) catch |err| {
+        log.err("API lookup failed: {}", .{err});
+        return null;
+    };
+
+    // Store in cache
+    self.cache.put(ip_u128, family, result) catch |err| {
+        log.warn("Failed to cache result: {}", .{err});
+    };
+
+    return result;
+}
+
+fn fetch(self: *Self, ip_str: []const u8) !Location {
+    log.info("Fetching geolocation for IP {s}", .{ip_str});
+
+    if (@import("builtin").is_test) return error.LookupUnavailableInUnitTest;
+
+    var buf: [256]u8 = undefined;
+    var w = std.Io.Writer.fixed(&buf);
+    try w.writeAll("https://ipwho.is/");
+    try w.writeAll(ip_str);
+    // Request only the fields we need
+    try w.writeAll("?fields=city,region,country,latitude,longitude&output=json");
+
+    var response_buf: [4096]u8 = undefined;
+    var writer = std.Io.Writer.fixed(&response_buf);
+    const result = try self.http_client.fetch(.{
+        .location = .{ .url = w.buffered() },
+        .method = .GET,
+        .response_writer = &writer,
+        .extra_headers = &.{
+            .{ .name = "User-Agent", .value = "wttr.in" },
+        },
+    });
+
+    if (result.status != .ok) {
+        log.err("API returned status {}", .{result.status});
+        return error.ApiError;
+    }
+
+    const response_body = response_buf[0..writer.end];
+
+    // Parse JSON response
+    const parsed = try std.json.parseFromSlice(
+        std.json.Value,
+        self.allocator,
+        response_body,
+        .{},
+    );
+    defer parsed.deinit();
+
+    const obj = parsed.value.object;
+
+    // Check for success field
+    if (obj.get("success")) |success| {
+        if (success == .bool and !success.bool) {
+            const msg = if (obj.get("message")) |m| if (m == .string) m.string else "unknown" else "unknown";
+            log.err("API returned error for ip {s}: {s}", .{ ip_str, msg });
+            return error.ApiError;
+        }
+    }
+
+    const lat = obj.get("latitude") orelse return error.MissingLatitude;
+    const lon = obj.get("longitude") orelse return error.MissingLongitude;
+    if (lat != .float and lat != .integer) {
+        log.err("Latitude returned from ipwho.is for ip {s} is not a number", .{ip_str});
+        return error.MissingLatitude;
+    }
+    if (lon != .float and lon != .integer) {
+        log.err("Longitude returned from ipwho.is for ip {s} is not a number", .{ip_str});
+        return error.MissingLongitude;
+    }
+
+    const city = getString(obj, "city");
+    const region = getString(obj, "region");
+    const country = getString(obj, "country");
+
+    const display_name = Location.buildDisplayName(
+        self.allocator,
+        city,
+        region,
+        country,
+        ip_str,
+    );
+
+    const lat_val: f64 = if (lat == .float) @floatCast(lat.float) else @floatFromInt(lat.integer);
+    const lon_val: f64 = if (lon == .float) @floatCast(lon.float) else @floatFromInt(lon.integer);
+
+    return Location{
+        .allocator = self.allocator,
+        .name = display_name,
+        .coords = .{
+            .latitude = lat_val,
+            .longitude = lon_val,
+        },
+    };
+}
+
+inline fn getString(obj: std.json.ObjectMap, key: []const u8) []const u8 {
+    const maybe_val = obj.get(key);
+    if (maybe_val == null) return "";
+    if (maybe_val.? != .string) return "";
+    return maybe_val.?.string;
+}
diff --git a/src/location/resolver.zig b/src/location/resolver.zig
index 295cf59..df35468 100644
--- a/src/location/resolver.zig
+++ b/src/location/resolver.zig
@@ -304,7 +304,7 @@ test "resolve IP address with GeoIP" {
         try GeoLite2.ensureDatabase(allocator, config.geolite_path);
     }
 
-    var geoip = GeoIp.init(allocator, config.geolite_path, null, config.ip2location_cache_file) catch
+    var geoip = GeoIp.init(allocator, config.geolite_path, config) catch
         return error.SkipZigTest;
     defer geoip.deinit();
 
diff --git a/src/main.zig b/src/main.zig
index 9b32bee..9bb9217 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -38,12 +38,11 @@ pub fn main() !u8 {
     // Ensure GeoLite2 database exists
     try GeoLite2.ensureDatabase(allocator, cfg.geolite_path);
 
-    // Initialize GeoIP database with optional IP2Location fallback
+    // Initialize GeoIP database with configured fallback
     var geoip = GeoIp.init(
         allocator,
         cfg.geolite_path,
-        cfg.ip2location_api_key,
-        cfg.ip2location_cache_file,
+        cfg,
     ) catch |err| {
         std.log.err("Failed to load GeoIP database from {s}: {}", .{ cfg.geolite_path, err });
         return err;
@@ -105,4 +104,5 @@ test {
     _ = @import("location/GeoCache.zig");
     _ = @import("location/Airports.zig");
     _ = @import("location/resolver.zig");
+    _ = @import("location/IpWhoIs.zig");
 }