diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5baa59d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+db
\ No newline at end of file
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..c17a7d8
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,46 @@
+module github.com/KorAP/Kalamar-Plugin-ExternalSale
+
+go 1.19
+
+require (
+	github.com/dgraph-io/badger/v3 v3.2103.5
+	github.com/gin-gonic/gin v1.8.1
+	github.com/stretchr/testify v1.7.1
+)
+
+require (
+	github.com/cespare/xxhash v1.1.0 // indirect
+	github.com/cespare/xxhash/v2 v2.1.1 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dgraph-io/ristretto v0.1.1 // indirect
+	github.com/dustin/go-humanize v1.0.0 // indirect
+	github.com/gin-contrib/sse v0.1.0 // indirect
+	github.com/go-playground/locales v0.14.0 // indirect
+	github.com/go-playground/universal-translator v0.18.0 // indirect
+	github.com/go-playground/validator/v10 v10.10.0 // indirect
+	github.com/goccy/go-json v0.9.7 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b // indirect
+	github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6 // indirect
+	github.com/golang/protobuf v1.5.0 // indirect
+	github.com/golang/snappy v0.0.3 // indirect
+	github.com/google/flatbuffers v1.12.1 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/compress v1.12.3 // indirect
+	github.com/leodido/go-urn v1.2.1 // indirect
+	github.com/mattn/go-isatty v0.0.14 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421 // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/pelletier/go-toml/v2 v2.0.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/ugorji/go/codec v1.2.7 // indirect
+	go.opencensus.io v0.22.5 // indirect
+	golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97 // indirect
+	golang.org/x/net v0.0.0-20210226172049-e18ecbb05110 // indirect
+	golang.org/x/sys v0.0.0-20221010170243-090e33056c14 // indirect
+	golang.org/x/text v0.3.6 // indirect
+	google.golang.org/protobuf v1.28.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..3deb7ef
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,206 @@
+cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/OneOfOne/xxhash v1.2.2 h1:KMrpdQIwFcEqXDklaen+P1axHaj9BSKzvpUUfnHldSE=
+github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
+github.com/armon/consul-api v0.0.0-20180202201655-eb2c6b5be1b6/go.mod h1:grANhF5doyWs3UAsr3K4I6qtAmlQcZDesFNEHPZAzj8=
+github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=
+github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
+github.com/cespare/xxhash/v2 v2.1.1 h1:6MnRN8NT7+YBpUIWxHtefFZOKTAPgGjpQSxqLNn0+qY=
+github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
+github.com/coreos/etcd v3.3.10+incompatible/go.mod h1:uF7uidLiAD3TWHmW31ZFd/JWoc32PjwdhPthX9715RE=
+github.com/coreos/go-etcd v2.0.0+incompatible/go.mod h1:Jez6KQU2B/sWsbdaef3ED8NzMklzPG4d5KIOhIy30Tk=
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diff --git a/service.go b/service.go
new file mode 100644
index 0000000..ba009b8
--- /dev/null
+++ b/service.go
@@ -0,0 +1,80 @@
+package main
+
+import (
+	"log"
+	"net/http"
+
+	badger "github.com/dgraph-io/badger/v3"
+	"github.com/gin-gonic/gin"
+)
+
+var db *badger.DB
+
+func CheckSaleUrl(c *gin.Context) {
+
+	corpusID := c.Param("corpus_id")
+	docID := c.Param("doc_id")
+	textID := c.Param("text_id")
+
+	err := db.View(func(txn *badger.Txn) error {
+
+		item, err := txn.Get([]byte(corpusID + "/" + docID + "/" + textID))
+
+		if err != nil {
+			c.String(http.StatusNotFound, "No entry found")
+		}
+
+		err = item.Value(func(v []byte) error {
+			c.String(http.StatusOK, string(v))
+			return nil
+		})
+
+		if err != nil {
+			c.String(http.StatusNotFound, err.Error())
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		c.String(http.StatusNotFound, err.Error())
+	}
+
+	c.String(http.StatusExpectationFailed, err.Error())
+}
+
+func add(corpusID, docID, textID string, url string) error {
+	err := db.Update(func(txn *badger.Txn) error {
+		err := txn.Set([]byte(corpusID+"/"+docID+"/"+textID), []byte(url))
+		return err
+	})
+	return err
+}
+
+func initDB(dir string) {
+	if db != nil {
+		return
+	}
+	var err error
+	db, err = badger.Open(badger.DefaultOptions(dir))
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func closeDB() {
+	db.Close()
+}
+
+func setupRouter() *gin.Engine {
+	r := gin.Default()
+	r.GET("/:corpus_id/:doc_id/:text_id", CheckSaleUrl)
+	return r
+}
+
+func main() {
+	initDB("db")
+	r := setupRouter()
+	r.Run(":8080")
+	defer closeDB()
+}
diff --git a/service_test.go b/service_test.go
new file mode 100644
index 0000000..a18c52e
--- /dev/null
+++ b/service_test.go
@@ -0,0 +1,35 @@
+package main
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPingRoute(t *testing.T) {
+
+	dir := t.TempDir()
+
+	initDB(dir)
+	defer closeDB()
+	router := setupRouter()
+
+	w := httptest.NewRecorder()
+	req, _ := http.NewRequest(http.MethodGet, "/s10/s10/s10", nil)
+
+	router.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusNotFound, w.Code)
+	assert.Equal(t, "No entry found", w.Body.String())
+
+	assert.Nil(t, add("s11", "s12", "s13", "http://example.org"))
+
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest(http.MethodGet, "/s11/s12/s13", nil)
+
+	router.ServeHTTP(w, req)
+	assert.Equal(t, http.StatusOK, w.Code)
+	assert.Equal(t, "http://example.org", w.Body.String())
+}