diff --git a/.gitignore b/.gitignore
index 345a707..0436191 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,7 @@
 credentials.tsv
+GeoIP.conf
+*.mmdb
+testdata
 
 .env
 *.env
@@ -7,6 +10,8 @@ env.*
 
 # Project binaries
 dist/
+/check-ip
+/cmd/check-ip/check-ip
 auth/csvauth/cmd/csvauth/csvauth
 cmd/auth-proxy/auth-proxy
 cmd/httplog/httplog
diff --git a/go.mod b/go.mod
index 0f9cd88..56051bb 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,11 @@
 module github.com/therootcompany/golib
 
 go 1.26.0
+
+require (
+	github.com/oschwald/geoip2-golang v1.13.0 // indirect
+	github.com/oschwald/maxminddb-golang v1.13.0 // indirect
+	github.com/phuslu/iploc v1.0.20260415 // indirect
+	golang.org/x/sys v0.20.0 // indirect
+	golang.org/x/time v0.15.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..b73aa37
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,10 @@
+github.com/oschwald/geoip2-golang v1.13.0 h1:Q44/Ldc703pasJeP5V9+aFSZFmBN7DKHbNsSFzQATJI=
+github.com/oschwald/geoip2-golang v1.13.0/go.mod h1:P9zG+54KPEFOliZ29i7SeYZ/GM6tfEL+rgSn03hYuUo=
+github.com/oschwald/maxminddb-golang v1.13.0 h1:R8xBorY71s84yO06NgTmQvqvTvlS/bnYZrrWX1MElnU=
+github.com/oschwald/maxminddb-golang v1.13.0/go.mod h1:BU0z8BfFVhi1LQaonTwwGQlsHUEu9pWNdMfmq4ztm0o=
+github.com/phuslu/iploc v1.0.20260415 h1:k0yQ1+kIgYAQXIp2OPp/CwbXpmuAwr/QsdY5lWnFnu8=
+github.com/phuslu/iploc v1.0.20260415/go.mod h1:VZqAWoi2A80YPvfk1AizLGHavNIG9nhBC8d87D/SeVs=
+golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
+golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/time v0.15.0 h1:bbrp8t3bGUeFOx08pvsMYRTCVSMk89u4tKbNOZbp88U=
+golang.org/x/time v0.15.0/go.mod h1:Y4YMaQmXwGQZoFaVFk4YpCt4FLQMYKZe9oeV/f4MSno=
diff --git a/go.work b/go.work
new file mode 100644
index 0000000..d8b4543
--- /dev/null
+++ b/go.work
@@ -0,0 +1,22 @@
+go 1.26.1
+
+use (
+	.
+	./cmd/check-ip
+	./cmd/form2mail
+	./net/formmailer
+	./net/geoip
+	./net/gitshallow
+	./net/httpcache
+	./net/ipcohort
+	./sync/dataset
+)
+
+replace (
+	github.com/therootcompany/golib/net/formmailer v0.0.0 => ./net/formmailer
+	github.com/therootcompany/golib/net/geoip v0.0.0 => ./net/geoip
+	github.com/therootcompany/golib/net/gitshallow v0.0.0 => ./net/gitshallow
+	github.com/therootcompany/golib/net/httpcache v0.0.0 => ./net/httpcache
+	github.com/therootcompany/golib/net/ipcohort v0.0.0 => ./net/ipcohort
+	github.com/therootcompany/golib/sync/dataset v0.0.0 => ./sync/dataset
+)
diff --git a/go.work.sum b/go.work.sum
new file mode 100644
index 0000000..07d502d
--- /dev/null
+++ b/go.work.sum
@@ -0,0 +1,7 @@
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/term v0.39.0/go.mod h1:yxzUCTP/U+FzoxfdKmLaA0RV1WgE0VY7hXBwKtY/4ww=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=