diff --git a/client/duneapi/batch.go b/client/duneapi/batch.go
new file mode 100644
index 0000000..dc98c9f
--- /dev/null
+++ b/client/duneapi/batch.go
@@ -0,0 +1,44 @@
+package duneapi
+
+import (
+	"encoding/json"
+	"io"
+
+	"github.com/duneanalytics/blockchain-ingester/models"
+)
+
+type BlockBatchHeader struct {
+	BlockSizes []int `json:"block_sizes"`
+}
+
+func WriteBlockBatch(out io.Writer, payloads []models.RPCBlock, disableHeader bool) error {
+	// we write a batch header (single line, NDJSON) with the size of each block payload and then concatenate the payloads
+	header := BlockBatchHeader{
+		BlockSizes: make([]int, len(payloads)),
+	}
+	for i, block := range payloads {
+		header.BlockSizes[i] = len(block.Payload)
+	}
+	// allow disabling the header for testing/backwards compatibility
+	if !disableHeader {
+		buf, err := json.Marshal(header)
+		if err != nil {
+			return err
+		}
+		_, err = out.Write(buf)
+		if err != nil {
+			return err
+		}
+		_, err = out.Write([]byte("\n"))
+		if err != nil {
+			return err
+		}
+	}
+	for _, block := range payloads {
+		_, err := out.Write(block.Payload)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
diff --git a/client/duneapi/batch_test.go b/client/duneapi/batch_test.go
new file mode 100644
index 0000000..b9c7ba8
--- /dev/null
+++ b/client/duneapi/batch_test.go
@@ -0,0 +1,95 @@
+package duneapi_test
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"io"
+	"testing"
+
+	"github.com/duneanalytics/blockchain-ingester/client/duneapi"
+	"github.com/duneanalytics/blockchain-ingester/models"
+	"github.com/stretchr/testify/require"
+)
+
+func TestWriteBlockBatch(t *testing.T) {
+	tests := []struct {
+		name     string
+		payloads []models.RPCBlock
+		expected string
+	}{
+		{
+			name: "single payload",
+			payloads: []models.RPCBlock{
+				{Payload: []byte(`{"block":1}`)},
+			},
+			expected: `{"block_sizes":[11]}
+{"block":1}`,
+		},
+		{
+			name: "multiple payloads, with new lines",
+			payloads: []models.RPCBlock{
+				{Payload: []byte(`{"block":1}` + "\n")},
+				{Payload: []byte(`{"block":2}` + "\n")},
+			},
+			expected: `{"block_sizes":[12,12]}
+{"block":1}
+{"block":2}
+`,
+		},
+		{
+			name: "multiple payloads, no newlines",
+			payloads: []models.RPCBlock{
+				{Payload: []byte(`{"block":1}`)},
+				{Payload: []byte(`{"block":2}`)},
+			},
+			expected: `{"block_sizes":[11,11]}
+{"block":1}{"block":2}`,
+		},
+		{
+			name:     "empty payloads",
+			payloads: []models.RPCBlock{},
+			expected: `{"block_sizes":[]}
+`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			err := duneapi.WriteBlockBatch(&buf, tt.payloads, false)
+			require.NoError(t, err)
+
+			require.Equal(t, tt.expected, buf.String())
+			rebuilt, err := ReadBlockBatch(&buf)
+			require.NoError(t, err)
+			require.EqualValues(t, tt.payloads, rebuilt)
+		})
+	}
+}
+
+func ReadBlockBatch(buf *bytes.Buffer) ([]models.RPCBlock, error) {
+	reader := bufio.NewReader(buf)
+	headerLine, err := reader.ReadString('\n')
+	if err != nil {
+		return nil, err
+	}
+
+	var header duneapi.BlockBatchHeader
+	err = json.Unmarshal([]byte(headerLine), &header)
+	if err != nil {
+		return nil, err
+	}
+
+	payloads := make([]models.RPCBlock, len(header.BlockSizes))
+	for i, size := range header.BlockSizes {
+		payload := make([]byte, size)
+		_, err := io.ReadFull(reader, payload)
+		if err != nil {
+			return nil, err
+		}
+		payloads[i] = models.RPCBlock{Payload: payload}
+	}
+
+	return payloads, nil
+}
diff --git a/client/duneapi/client.go b/client/duneapi/client.go
index b91e114..37f2342 100644
--- a/client/duneapi/client.go
+++ b/client/duneapi/client.go
@@ -101,33 +101,28 @@ func (c *client) SendBlocks(ctx context.Context, payloads []models.RPCBlock) err
 
 func (c *client) buildRequest(payloads []models.RPCBlock, buffer *bytes.Buffer) (*BlockchainIngestRequest, error) {
 	request := &BlockchainIngestRequest{}
+	var err error
 
+	buffer.Reset()
 	// not thread safe, multiple calls to the compressor here
 	if c.cfg.DisableCompression {
-		buffer.Reset()
-		for _, block := range payloads {
-			_, err := buffer.Write(block.Payload)
-			if err != nil {
-				return nil, err
-			}
+		err = WriteBlockBatch(buffer, payloads, c.cfg.DisableBatchHeader)
+		if err != nil {
+			return nil, err
 		}
-		request.Payload = buffer.Bytes()
 	} else {
-		buffer.Reset()
 		c.compressor.Reset(buffer)
-		for _, block := range payloads {
-			_, err := c.compressor.Write(block.Payload)
-			if err != nil {
-				return nil, err
-			}
+		err = WriteBlockBatch(c.compressor, payloads, c.cfg.DisableBatchHeader)
+		if err != nil {
+			return nil, err
 		}
 		err := c.compressor.Close()
 		if err != nil {
 			return nil, err
 		}
 		request.ContentEncoding = "application/zstd"
-		request.Payload = buffer.Bytes()
 	}
+	request.Payload = buffer.Bytes()
 
 	numbers := make([]string, len(payloads))
 	for i, payload := range payloads {
@@ -137,6 +132,7 @@ func (c *client) buildRequest(payloads []models.RPCBlock, buffer *bytes.Buffer)
 	request.BlockNumbers = blockNumbers
 	request.IdempotencyKey = c.idempotencyKey(*request)
 	request.EVMStack = c.cfg.Stack.String()
+	request.BatchSize = len(payloads)
 	return request, nil
 }
 
@@ -281,6 +277,7 @@ func (c *client) PostProgressReport(ctx context.Context, progress models.Blockch
 	if err != nil {
 		return err
 	}
+	req.Header.Set("User-Agent", userAgent)
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("x-dune-api-key", c.cfg.APIKey)
 	req = req.WithContext(ctx)
diff --git a/client/duneapi/models.go b/client/duneapi/models.go
index 0a1e12e..c8148f1 100644
--- a/client/duneapi/models.go
+++ b/client/duneapi/models.go
@@ -22,6 +22,8 @@ type Config struct {
 	// - lowers latency
 	// - reduces bandwidth
 	DisableCompression bool
+
+	DisableBatchHeader bool // for testing/backwards compatibility
 }
 
 // The response from the DuneAPI ingest endpoint.
diff --git a/cmd/main.go b/cmd/main.go
index 6b1448c..c648542 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -57,6 +57,7 @@ func main() {
 		BlockchainName:     cfg.BlockchainName,
 		Stack:              cfg.RPCStack,
 		DisableCompression: cfg.DisableCompression,
+		DisableBatchHeader: cfg.Dune.DisableBatchHeader,
 	})
 	if err != nil {
 		stdlog.Fatal(err)
diff --git a/config/config.go b/config/config.go
index 94d2f9d..e50cf04 100644
--- a/config/config.go
+++ b/config/config.go
@@ -11,8 +11,9 @@ import (
 )
 
 type DuneClient struct {
-	APIKey string `long:"dune-api-key" env:"DUNE_API_KEY" description:"API key for DuneAPI"`
-	URL    string `long:"dune-api-url" env:"DUNE_API_URL" description:"URL for DuneAPI" default:"https://api.dune.com"`
+	APIKey             string `long:"dune-api-key" env:"DUNE_API_KEY" description:"API key for DuneAPI"`
+	URL                string `long:"dune-api-url" env:"DUNE_API_URL" description:"URL for DuneAPI" default:"https://api.dune.com"`                                    // nolint:lll
+	DisableBatchHeader bool   `long:"duneapi-disable-batch-header" env:"DUNEAPI_DISABLE_BATCH_HEADERS" description:"Disable batch headers on DuneAPI request payload"` // nolint:lll
 }
 
 func (d DuneClient) HasError() error {