diff --git a/data/data_reader.go b/data/data_reader.go
new file mode 100644
index 0000000..008ccec
--- /dev/null
+++ b/data/data_reader.go
@@ -0,0 +1,32 @@
+package data
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+)
+
+type Sample struct {
+	StartHeight   int64    `json:"start_height"`
+	HeaderStrings []string `json:"header_strings"`
+}
+
+func ReadJson(jsonFilePath string) (int64, []string, error) {
+	jsonFile, err := os.Open(jsonFilePath)
+	if err != nil {
+		return 0, nil, err
+	}
+	defer jsonFile.Close()
+
+	byteValue, err := io.ReadAll(jsonFile)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	var dataContent Sample
+	if err := json.Unmarshal(byteValue, &dataContent); err != nil {
+		return 0, nil, err
+	}
+
+	return dataContent.StartHeight, dataContent.HeaderStrings, nil
+}
diff --git a/data/empty.json b/data/empty.json
new file mode 100644
index 0000000..0139b5e
--- /dev/null
+++ b/data/empty.json
@@ -0,0 +1,4 @@
+{
+    "start_height": 1,
+    "header_strings": []
+}
\ No newline at end of file
diff --git a/data/regtest.json b/data/regtest.json
new file mode 100644
index 0000000..22cf335
--- /dev/null
+++ b/data/regtest.json
@@ -0,0 +1,15 @@
+{
+    "start_height": 11,
+    "header_strings": [
+        "4a8cb347715524caa17d43987d527d0c11c0510f3e3c44a85035038a9b36e338",
+        "568cd25931996e14d7b41a73dbf8306e4a0435eeab92aa23bb4005d69f911348",
+        "3b86a885250999e7c77465270553155369f39639c9f6d1caddfa1bdbbaaf8f7d",
+        "1ca9f0e3344df7ca4b95145ef1afd48b445d1d80cdf941ea91083ea186caaa50",
+        "508256b96ee547e87537e7c8c4f38da6c84201fe2eb29e919bc5b91c832e0d34",
+        "209b48cc83546d45fc1c50530cd532dbde1c4133445b635230e063ddeef2f30f",
+        "4737364655eb928ff741fb0276cec9c00f9d12cb7a6a30d556989bd8763072f9",
+        "5b9c7b979cbd4a382b32be69ae35f4db59b3795ae33d6462c0425f5ad05d9ebd",
+        "627ff72e849340d9cbd7603fc9ac884132d4886a6ddfbfd0f9b964142aa8e447",
+        "497cf112e892b9551bfe72deedfdad8deb5d4fed2fcbba2ba3bc9ae9f143c2af"
+    ]
+}
\ No newline at end of file
diff --git a/data/sample.json b/data/sample.json
new file mode 100644
index 0000000..f61ee9b
--- /dev/null
+++ b/data/sample.json
@@ -0,0 +1,18 @@
+{
+    "start_height": 204100,
+    "header_strings": [
+        "020000004cdba1415b2c6e7808c1b3c18df1374238454f7104203475bf01000000000000c17ea9d06015dc83902911cd24837a8ba4bdc0c1d72b873f906d921e06e48d2f984a8250ef75051a72a8061a",
+        "01000000a7e267eae437f7c99115682d3e104999b6b5b01f34f3f5d763030000000000004beb49a1caa3941adc853cd605dd030e5ab690fcd58ac76233397653c49f07ecdb4a8250ef75051a5e58c1fe",
+        "0100000032e89326a365919ac08d1f0bd98d097240fd5c8dd21b7c38e5030000000000003d3645c6e6008583570d618041b2452497d55c0cb936529af92f8191e0dbdcc9764b8250ef75051ac733c738",
+        "010000006cb4d23bba90d14f11d0719a02bdb0218e7b9a82a4453e0a51010000000000007caa984f729a85cec6ce000b87894bb30897195d36bc6491be92e7628de00d02e54d8250ef75051ac9b86274",
+        "01000000a5a2223dc3f0a3f7901d14d064216d6ecf9d5dabfa44199f2b02000000000000e877c5cb9c52e27e3b2b9ff5d3b1658bd5c49ce2e3a1ef608759b44eea5f832b424e8250ef75051a47a25741",
+        "0100000096bacf353c5534bc30044268588fb752df9c164a3ad14bd64d04000000000000a25ec7252a9a994d864b664bb4c5a2b1d8c1d688dc82ab78128eae34481110f416518250ef75051a1ac7889f",
+        "020000009c37b58365fedc02e5ce0fa879e14d3ec110a3700b6476b941000000000000007e82e8388e953e200ab3e41777e4f9982ce3fe3aa46cc29a8c8f974706f76f852b508250ef75051a9e6f81c1",
+        "010000001f7db2278bb6aeac530fa48e0f8e75cae092a89b6cbedb838500000000000000d7dfbe2005869b3319244192ba2fef1b0c9f1cf999da51be7d8f1a7f5bb02c6bf0538250ef75051a82d85a5f",
+        "01000000575cdd3be997ebc63b377e78ecde7f14ef354669ff7d62543703000000000000a7b0a3354071262e02c246ad1d49d6823f6d864aef247263a07641a1d419089b5a5a8250ef75051a1e7d568e",
+        "01000000fb49bbe46f780f8b0aa4b99ceddf1202e76d12fa4f5da1acdf000000000000003ec200da269c721728c820e305d01d4656e4ba0f6784c4fdeea05a904e0f0aab395d8250ef75051ac332b7b5",
+        "02000000418574a33d0657d095a8ff4723e8e1fafedcabe32b93d1ccf6010000000000006f95d48f47f27715f6c1bcc466c4c715a17f9e2be39ce1c41106baed2d146d546f5f8250ef75051a77fc3e40",
+        "01000000d19ffbe9a876f329acb05feadc90dae27578762e3f538f5a08050000000000005c8524057100e644fb3680b5b5af3d79f24fc4e51f374d9205e926e9b9cafd9c38648250ef75051a20379982",
+        "02000000670ffede95831fb41c09d0d104285d6182ce1c8577da40506405000000000000e54435f50bfc776b8f3d9ac047963ee6bdddd8d40b69236b4d97acb52a1fdce41e678250ef75051a88842656"
+    ]
+}
\ No newline at end of file
diff --git a/main.go b/main.go
index 7f717aa..0796bbe 100644
--- a/main.go
+++ b/main.go
@@ -8,29 +8,32 @@ import (
 	"github.com/gonative-cc/bitcoin-lightclient/btclightclient"
 	"github.com/gonative-cc/bitcoin-lightclient/rpcserver"
 
+	"github.com/gonative-cc/bitcoin-lightclient/data"
+
 	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/rs/zerolog/log"
 )
 
 func main() {
-	startHeight := 204100
-	headerStrings := []string{
-		`020000004cdba1415b2c6e7808c1b3c18df1374238454f7104203475bf01000000000000c17ea9d06015dc83902911cd24837a8ba4bdc0c1d72b873f906d921e06e48d2f984a8250ef75051a72a8061a`,
-		`01000000a7e267eae437f7c99115682d3e104999b6b5b01f34f3f5d763030000000000004beb49a1caa3941adc853cd605dd030e5ab690fcd58ac76233397653c49f07ecdb4a8250ef75051a5e58c1fe`,
-		`0100000032e89326a365919ac08d1f0bd98d097240fd5c8dd21b7c38e5030000000000003d3645c6e6008583570d618041b2452497d55c0cb936529af92f8191e0dbdcc9764b8250ef75051ac733c738`,
-		`010000006cb4d23bba90d14f11d0719a02bdb0218e7b9a82a4453e0a51010000000000007caa984f729a85cec6ce000b87894bb30897195d36bc6491be92e7628de00d02e54d8250ef75051ac9b86274`,
-		`01000000a5a2223dc3f0a3f7901d14d064216d6ecf9d5dabfa44199f2b02000000000000e877c5cb9c52e27e3b2b9ff5d3b1658bd5c49ce2e3a1ef608759b44eea5f832b424e8250ef75051a47a25741`,
-		`0100000096bacf353c5534bc30044268588fb752df9c164a3ad14bd64d04000000000000a25ec7252a9a994d864b664bb4c5a2b1d8c1d688dc82ab78128eae34481110f416518250ef75051a1ac7889f`,
-		`020000009c37b58365fedc02e5ce0fa879e14d3ec110a3700b6476b941000000000000007e82e8388e953e200ab3e41777e4f9982ce3fe3aa46cc29a8c8f974706f76f852b508250ef75051a9e6f81c1`,
-		`010000001f7db2278bb6aeac530fa48e0f8e75cae092a89b6cbedb838500000000000000d7dfbe2005869b3319244192ba2fef1b0c9f1cf999da51be7d8f1a7f5bb02c6bf0538250ef75051a82d85a5f`,
-		`01000000575cdd3be997ebc63b377e78ecde7f14ef354669ff7d62543703000000000000a7b0a3354071262e02c246ad1d49d6823f6d864aef247263a07641a1d419089b5a5a8250ef75051a1e7d568e`,
-		`01000000fb49bbe46f780f8b0aa4b99ceddf1202e76d12fa4f5da1acdf000000000000003ec200da269c721728c820e305d01d4656e4ba0f6784c4fdeea05a904e0f0aab395d8250ef75051ac332b7b5`,
-		`02000000418574a33d0657d095a8ff4723e8e1fafedcabe32b93d1ccf6010000000000006f95d48f47f27715f6c1bcc466c4c715a17f9e2be39ce1c41106baed2d146d546f5f8250ef75051a77fc3e40`,
-		`01000000d19ffbe9a876f329acb05feadc90dae27578762e3f538f5a08050000000000005c8524057100e644fb3680b5b5af3d79f24fc4e51f374d9205e926e9b9cafd9c38648250ef75051a20379982`,
-		`02000000670ffede95831fb41c09d0d104285d6182ce1c8577da40506405000000000000e54435f50bfc776b8f3d9ac047963ee6bdddd8d40b69236b4d97acb52a1fdce41e678250ef75051a88842656`,
+	// read the json file
+	// example: ./data/sample.json
+	if len(os.Args) < 2 {
+		log.Error().Msg("Missing filename.\nUsage: bitcoin-lightclient <sample_file.json>")
+		return
+	}
+	sampleFilename := os.Args[1]
+
+	if _, err := os.Stat(sampleFilename); os.IsNotExist(err) {
+		log.Error().Msgf("Sample file does not exist: %s", sampleFilename)
+		return
 	}
 
+	startHeight, headerStrings, err := data.ReadJson(sampleFilename)
+	if err != nil {
+		log.Error().Msgf("Error reading data file: %s", err)
+		return
+	}
 	headers := make([]wire.BlockHeader, len(headerStrings))
 
 	for id, headerStr := range headerStrings {
@@ -38,7 +41,7 @@ func main() {
 		headers[id] = h
 	}
 
-	btcLC := btclightclient.NewBTCLightClientWithData(&chaincfg.MainNetParams, headers, startHeight)
+	btcLC := btclightclient.NewBTCLightClientWithData(&chaincfg.MainNetParams, headers, int(startHeight))
 	btcLC.Status()
 
 	rpcService := rpcserver.NewRPCServer(btcLC)