diff --git a/cmd/hnanalytics/main.go b/cmd/hnanalytics/main.go
index 7264819..db8a949 100644
--- a/cmd/hnanalytics/main.go
+++ b/cmd/hnanalytics/main.go
@@ -2,21 +2,54 @@ package main
 
 import (
 	"context"
+	"flag"
 	"fmt"
 	"log"
+	"time"
 
+	"hnanalytics/internal/ingest/bigquery"
 	"hnanalytics/internal/whoishiring"
 )
 
+const dateLayout = "2006-01-02"
+
 func main() {
 	ctx := context.Background()
 
-	svc, err := whoishiring.NewService(ctx, "whoishiring.db")
+	source := flag.String("source", "api", "ingestion source: api or bigquery")
+	dbName := flag.String("db", "whoishiring.db", "datastore base name")
+	startDate := flag.String("start-date", "", "start date (YYYY-MM-DD), inclusive")
+	endDate := flag.String("end-date", "", "end date (YYYY-MM-DD), inclusive")
+	incremental := flag.Bool("incremental", false, "run incremental sync mode")
+	projectID := flag.String("gcp-project", "", "GCP project for BigQuery jobs")
+	location := flag.String("gcp-location", "", "BigQuery job location, e.g. US")
+	maxBytesBilled := flag.Int64("max-bytes-billed", 0, "optional BigQuery max bytes billed")
+	flag.Parse()
+
+	svc, err := whoishiring.NewService(ctx, *dbName)
 	if err != nil {
 		log.Fatal(err)
 	}
-	defer svc.Close()
+	defer func() {
+		if err := svc.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
 
+	switch *source {
+	case "api":
+		runAPISource(ctx, svc)
+	case "bigquery":
+		cfg := bigquery.Config{ProjectID: *projectID, Location: *location, MaxBytesBilled: *maxBytesBilled}
+		if err := runBigQuerySource(ctx, svc, cfg, *startDate, *endDate, *incremental); err != nil {
+			log.Fatal(err)
+		}
+	default:
+		log.Fatalf("unsupported source %q", *source)
+	}
+}
+
+func runAPISource(ctx context.Context, svc *whoishiring.Service) {
 	users := []string{"whoishiring", "_whoishiring"}
 	for _, user := range users {
 		scrapedUser, err := svc.ScrapeUser(ctx, user)
@@ -49,3 +82,84 @@ func main() {
 	}
 	fmt.Printf("Processed %d analytic items\n", len(analyticItems))
 }
+
+func runBigQuerySource(ctx context.Context, svc *whoishiring.Service, cfg bigquery.Config, startDate, endDate string, incremental bool) error {
+	source, err := bigquery.New(ctx, cfg)
+	if err != nil {
+		return err
+	}
+	defer source.Close()
+
+	if incremental {
+		return runBigQueryIncremental(ctx, svc, source, endDate)
+	}
+	if startDate == "" || endDate == "" {
+		return fmt.Errorf("start-date and end-date are required for backfill")
+	}
+	start, end, err := parseDateRange(startDate, endDate)
+	if err != nil {
+		return err
+	}
+
+	items, watermark, err := source.BackfillByDateRange(ctx, start, end)
+	if err != nil {
+		return err
+	}
+	inserted := svc.UpsertAnalyticItems(ctx, items)
+	if len(items) > 0 {
+		svc.SetCheckpoint(ctx, "bigquery", whoishiring.Checkpoint{Time: watermark.Time, ID: watermark.ID})
+	}
+	fmt.Printf("Backfilled %d items (%d inserted new rows).\n", len(items), inserted)
+	return nil
+}
+
+func runBigQueryIncremental(ctx context.Context, svc *whoishiring.Service, source *bigquery.Source, endDate string) error {
+	watermark := bigquery.Watermark{}
+	if cp, ok := svc.GetCheckpoint(ctx, "bigquery"); ok {
+		watermark = bigquery.Watermark{Time: cp.Time, ID: cp.ID}
+	}
+
+	upperBound := time.Now().UTC().Truncate(24 * time.Hour).Add(24 * time.Hour)
+	if endDate != "" {
+		end, err := parseDate(endDate)
+		if err != nil {
+			return err
+		}
+		upperBound = end.Add(24 * time.Hour)
+	}
+
+	items, latest, err := source.SyncIncremental(ctx, watermark, upperBound)
+	if err != nil {
+		return err
+	}
+	inserted := svc.UpsertAnalyticItems(ctx, items)
+	if len(items) > 0 {
+		svc.SetCheckpoint(ctx, "bigquery", whoishiring.Checkpoint{Time: latest.Time, ID: latest.ID})
+	}
+	fmt.Printf("Incremental sync returned %d items (%d inserted new rows).\n", len(items), inserted)
+	return nil
+}
+
+func parseDateRange(startDate, endDate string) (time.Time, time.Time, error) {
+	start, err := parseDate(startDate)
+	if err != nil {
+		return time.Time{}, time.Time{}, err
+	}
+	end, err := parseDate(endDate)
+	if err != nil {
+		return time.Time{}, time.Time{}, err
+	}
+	endExclusive := end.Add(24 * time.Hour)
+	if !start.Before(endExclusive) {
+		return time.Time{}, time.Time{}, fmt.Errorf("start-date must be before or equal to end-date")
+	}
+	return start, endExclusive, nil
+}
+
+func parseDate(value string) (time.Time, error) {
+	parsed, err := time.Parse(dateLayout, value)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("invalid date %q: %w", value, err)
+	}
+	return parsed.UTC(), nil
+}
diff --git a/go.mod b/go.mod
index 927f391..3e437a5 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,54 @@
 module hnanalytics
 
-go 1.22
+go 1.24.0
+
+require (
+	cloud.google.com/go/bigquery v1.73.1
+	google.golang.org/api v0.267.0
+)
+
+require (
+	cloud.google.com/go v0.123.0 // indirect
+	cloud.google.com/go/auth v0.18.1 // indirect
+	cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
+	cloud.google.com/go/compute/metadata v0.9.0 // indirect
+	cloud.google.com/go/iam v1.5.3 // indirect
+	github.com/apache/arrow/go/v15 v15.0.2 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/goccy/go-json v0.10.2 // indirect
+	github.com/google/flatbuffers v23.5.26+incompatible // indirect
+	github.com/google/s2a-go v0.1.9 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.11 // indirect
+	github.com/googleapis/gax-go/v2 v2.17.0 // indirect
+	github.com/klauspost/compress v1.16.7 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.5 // indirect
+	github.com/pierrec/lz4/v4 v4.1.18 // indirect
+	github.com/zeebo/xxh3 v1.0.2 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.63.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.61.0 // indirect
+	go.opentelemetry.io/otel v1.39.0 // indirect
+	go.opentelemetry.io/otel/metric v1.39.0 // indirect
+	go.opentelemetry.io/otel/trace v1.39.0 // indirect
+	golang.org/x/crypto v0.47.0 // indirect
+	golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 // indirect
+	golang.org/x/mod v0.31.0 // indirect
+	golang.org/x/net v0.49.0 // indirect
+	golang.org/x/oauth2 v0.35.0 // indirect
+	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/sys v0.40.0 // indirect
+	golang.org/x/telemetry v0.0.0-20251203150158-8fff8a5912fc // indirect
+	golang.org/x/text v0.33.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
+	golang.org/x/tools v0.40.0 // indirect
+	golang.org/x/xerrors v0.0.0-20240903120638-7835f813f4da // indirect
+	google.golang.org/genproto v0.0.0-20260128011058-8636f8732409 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20260128011058-8636f8732409 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260203192932-546029d2fa20 // indirect
+	google.golang.org/grpc v1.78.0 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..6e9e36b
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,145 @@
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+cel.dev/expr v0.24.0/go.mod h1:hLPLo1W4QUmuYdA72RBX06QTs6MXw941piREPl3Yfiw=
+cloud.google.com/go v0.123.0 h1:2NAUJwPR47q+E35uaJeYoNhuNEM9kM8SjgRgdeOJUSE=
+cloud.google.com/go v0.123.0/go.mod h1:xBoMV08QcqUGuPW65Qfm1o9Y4zKZBpGS+7bImXLTAZU=
+cloud.google.com/go/auth v0.18.1 h1:IwTEx92GFUo2pJ6Qea0EU3zYvKnTAeRCODxfA/G5UWs=
+cloud.google.com/go/auth v0.18.1/go.mod h1:GfTYoS9G3CWpRA3Va9doKN9mjPGRS+v41jmZAhBzbrA=
+cloud.google.com/go/auth/oauth2adapt v0.2.8 h1:keo8NaayQZ6wimpNSmW5OPc283g65QNIiLpZnkHRbnc=
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+cloud.google.com/go/bigquery v1.73.1 h1:v//GZwdhtmCbZ87rOnxz7pectOGFS1GNRvrGTvLzka4=
+cloud.google.com/go/bigquery v1.73.1/go.mod h1:KSLx1mKP/yGiA8U+ohSrqZM1WknUnjZAxHAQZ51/b1k=
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diff --git a/internal/ingest/bigquery/source.go b/internal/ingest/bigquery/source.go
new file mode 100644
index 0000000..07e3f29
--- /dev/null
+++ b/internal/ingest/bigquery/source.go
@@ -0,0 +1,150 @@
+package bigquery
+
+import (
+	"context"
+	"fmt"
+	"math"
+	"time"
+
+	gcbigquery "cloud.google.com/go/bigquery"
+	"google.golang.org/api/iterator"
+
+	"hnanalytics/internal/whoishiring"
+)
+
+const (
+	defaultDataset = "bigquery-public-data.hacker_news"
+	defaultTable   = "full"
+)
+
+type Config struct {
+	ProjectID      string
+	Location       string
+	MaxBytesBilled int64
+	Dataset        string
+	Table          string
+}
+
+type Watermark struct {
+	Time time.Time
+	ID   int
+}
+
+type Source struct {
+	client *gcbigquery.Client
+	cfg    Config
+}
+
+type row struct {
+	ID    int64                 `bigquery:"id"`
+	Time  time.Time             `bigquery:"time"`
+	Title gcbigquery.NullString `bigquery:"title"`
+	Dead  gcbigquery.NullBool   `bigquery:"dead"`
+	Kids  []int64               `bigquery:"kids"`
+}
+
+func New(ctx context.Context, cfg Config) (*Source, error) {
+	if cfg.ProjectID == "" {
+		return nil, fmt.Errorf("project id is required")
+	}
+	if cfg.Dataset == "" {
+		cfg.Dataset = defaultDataset
+	}
+	if cfg.Table == "" {
+		cfg.Table = defaultTable
+	}
+
+	client, err := gcbigquery.NewClient(ctx, cfg.ProjectID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Source{client: client, cfg: cfg}, nil
+}
+
+func (s *Source) Close() error { return s.client.Close() }
+
+func (s *Source) BackfillByDateRange(ctx context.Context, startInclusive, endExclusive time.Time) ([]whoishiring.AnalyticItem, Watermark, error) {
+	if !startInclusive.Before(endExclusive) {
+		return nil, Watermark{}, fmt.Errorf("start must be before end")
+	}
+
+	query := fmt.Sprintf("\nSELECT\n  id,\n  time,\n  title,\n  dead,\n  kids\nFROM `%s.%s`\nWHERE time >= @start_time\n  AND time < @end_time\nORDER BY time ASC, id ASC", s.cfg.Dataset, s.cfg.Table)
+
+	rows, err := s.readRows(ctx, query, []gcbigquery.QueryParameter{
+		{Name: "start_time", Value: startInclusive},
+		{Name: "end_time", Value: endExclusive},
+	})
+	if err != nil {
+		return nil, Watermark{}, err
+	}
+	return toAnalyticItems(rows)
+}
+
+func (s *Source) SyncIncremental(ctx context.Context, watermark Watermark, upperBoundExclusive time.Time) ([]whoishiring.AnalyticItem, Watermark, error) {
+	query := fmt.Sprintf("\nSELECT\n  id,\n  time,\n  title,\n  dead,\n  kids\nFROM `%s.%s`\nWHERE (time > @watermark_time OR (time = @watermark_time AND id > @watermark_id))\n  AND time < @upper_bound\nORDER BY time ASC, id ASC", s.cfg.Dataset, s.cfg.Table)
+
+	rows, err := s.readRows(ctx, query, []gcbigquery.QueryParameter{
+		{Name: "watermark_time", Value: watermark.Time},
+		{Name: "watermark_id", Value: watermark.ID},
+		{Name: "upper_bound", Value: upperBoundExclusive},
+	})
+	if err != nil {
+		return nil, watermark, err
+	}
+	return toAnalyticItems(rows)
+}
+
+func (s *Source) readRows(ctx context.Context, queryText string, params []gcbigquery.QueryParameter) ([]row, error) {
+	query := s.client.Query(queryText)
+	query.Parameters = params
+	if s.cfg.Location != "" {
+		query.Location = s.cfg.Location
+	}
+	if s.cfg.MaxBytesBilled > 0 {
+		query.MaxBytesBilled = s.cfg.MaxBytesBilled
+	}
+
+	it, err := query.Read(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	rows := make([]row, 0)
+	for {
+		var r row
+		err := it.Next(&r)
+		if err == iterator.Done {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		rows = append(rows, r)
+	}
+	return rows, nil
+}
+
+func toAnalyticItems(rows []row) ([]whoishiring.AnalyticItem, Watermark, error) {
+	analytics := make([]whoishiring.AnalyticItem, 0, len(rows))
+	wm := Watermark{}
+	for _, r := range rows {
+		if r.Dead.Valid && r.Dead.Bool {
+			continue
+		}
+		if r.ID > math.MaxInt {
+			return nil, Watermark{}, fmt.Errorf("row id %d overflows int", r.ID)
+		}
+
+		var title *string
+		if r.Title.Valid {
+			t := r.Title.StringVal
+			title = &t
+		}
+
+		analytic := whoishiring.AnalyticItemFromFields(int(r.ID), r.Time.UTC(), title, len(r.Kids))
+		analytics = append(analytics, analytic)
+		wm = Watermark{Time: r.Time.UTC(), ID: int(r.ID)}
+	}
+	return analytics, wm, nil
+}
diff --git a/internal/ingest/bigquery/source_test.go b/internal/ingest/bigquery/source_test.go
new file mode 100644
index 0000000..50af74f
--- /dev/null
+++ b/internal/ingest/bigquery/source_test.go
@@ -0,0 +1,30 @@
+package bigquery
+
+import (
+	"testing"
+	"time"
+
+	gcbigquery "cloud.google.com/go/bigquery"
+)
+
+func TestToAnalyticItems(t *testing.T) {
+	title := "Ask HN: Who is hiring? (June 2024)"
+	rows := []row{
+		{ID: 10, Time: time.Unix(100, 0), Title: gcbigquery.NullString{StringVal: title, Valid: true}, Kids: []int64{1, 2}},
+		{ID: 11, Time: time.Unix(101, 0), Dead: gcbigquery.NullBool{Bool: true, Valid: true}},
+	}
+
+	items, watermark, err := toAnalyticItems(rows)
+	if err != nil {
+		t.Fatalf("toAnalyticItems() error = %v", err)
+	}
+	if len(items) != 1 {
+		t.Fatalf("expected 1 item, got %d", len(items))
+	}
+	if items[0].WHType != "hiring" {
+		t.Fatalf("expected hiring item type, got %q", items[0].WHType)
+	}
+	if watermark.ID != 10 {
+		t.Fatalf("expected watermark id 10, got %d", watermark.ID)
+	}
+}
diff --git a/internal/whoishiring/service.go b/internal/whoishiring/service.go
index 8872740..18fd570 100644
--- a/internal/whoishiring/service.go
+++ b/internal/whoishiring/service.go
@@ -35,6 +35,13 @@ type dataStore struct {
 	ScrapeUsers   map[string][]userRecord `json:"scrape_users"`
 	ScrapeItems   map[int]itemRecord      `json:"scrape_items"`
 	AnalyticItems map[int]AnalyticItem    `json:"analytic_items"`
+	Checkpoints   map[string]Checkpoint   `json:"checkpoints"`
+}
+
+type Checkpoint struct {
+	Time      time.Time `json:"time"`
+	ID        int       `json:"id"`
+	UpdatedAt time.Time `json:"updated_at"`
 }
 
 type userRecord struct {
@@ -116,6 +123,7 @@ func NewService(_ context.Context, dbName string) (*Service, error) {
 			ScrapeUsers:   map[string][]userRecord{},
 			ScrapeItems:   map[int]itemRecord{},
 			AnalyticItems: map[int]AnalyticItem{},
+			Checkpoints:   map[string]Checkpoint{},
 		},
 	}
 
@@ -136,7 +144,24 @@ func (s *Service) load() error {
 	if err != nil {
 		return err
 	}
-	return json.Unmarshal(content, &s.store)
+	if err := json.Unmarshal(content, &s.store); err != nil {
+		return err
+	}
+
+	if s.store.ScrapeUsers == nil {
+		s.store.ScrapeUsers = map[string][]userRecord{}
+	}
+	if s.store.ScrapeItems == nil {
+		s.store.ScrapeItems = map[int]itemRecord{}
+	}
+	if s.store.AnalyticItems == nil {
+		s.store.AnalyticItems = map[int]AnalyticItem{}
+	}
+	if s.store.Checkpoints == nil {
+		s.store.Checkpoints = map[string]Checkpoint{}
+	}
+
+	return nil
 }
 
 func (s *Service) persist() error {
@@ -299,11 +324,14 @@ func (s *Service) ScrapeToAnalyticItems(_ context.Context) ([]AnalyticItem, erro
 }
 
 func toAnalyticItem(item Item) AnalyticItem {
-	kidsCount := len(item.Kids)
+	return AnalyticItemFromFields(item.ID, item.Time, item.Title, len(item.Kids))
+}
+
+func AnalyticItemFromFields(id int, createTime time.Time, title *string, kidsCount int) AnalyticItem {
 	whType := "other"
 
-	if item.Title != nil {
-		title := strings.ToLower(*item.Title)
+	if title != nil {
+		title := strings.ToLower(*title)
 		switch {
 		case strings.HasPrefix(title, freelancerTitle):
 			whType = "freelancer"
@@ -314,7 +342,38 @@ func toAnalyticItem(item Item) AnalyticItem {
 		}
 	}
 
-	return AnalyticItem{ID: item.ID, CreateTime: item.Time, WHType: whType, NumKids: kidsCount}
+	return AnalyticItem{ID: id, CreateTime: createTime, WHType: whType, NumKids: kidsCount}
+}
+
+func (s *Service) UpsertAnalyticItems(_ context.Context, items []AnalyticItem) int {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	count := 0
+	for _, item := range items {
+		if _, exists := s.store.AnalyticItems[item.ID]; !exists {
+			count++
+		}
+		s.store.AnalyticItems[item.ID] = item
+	}
+
+	return count
+}
+
+func (s *Service) GetCheckpoint(_ context.Context, key string) (Checkpoint, bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	cp, ok := s.store.Checkpoints[key]
+	return cp, ok
+}
+
+func (s *Service) SetCheckpoint(_ context.Context, key string, checkpoint Checkpoint) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	checkpoint.UpdatedAt = time.Now().UTC()
+	s.store.Checkpoints[key] = checkpoint
 }
 
 func (s *Service) fetch(ctx context.Context, url string) ([]byte, error) {
diff --git a/internal/whoishiring/service_test.go b/internal/whoishiring/service_test.go
index 52cc244..a5fc85b 100644
--- a/internal/whoishiring/service_test.go
+++ b/internal/whoishiring/service_test.go
@@ -1,6 +1,8 @@
 package whoishiring
 
 import (
+	"context"
+	"os"
 	"testing"
 	"time"
 )
@@ -37,3 +39,35 @@ func TestToAnalyticItem(t *testing.T) {
 		t.Fatalf("expected 3 kids, got %d", analytic.NumKids)
 	}
 }
+
+func TestUpsertAnalyticItemsAndCheckpoint(t *testing.T) {
+	dir := t.TempDir()
+	oldWD, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("Getwd() error = %v", err)
+	}
+	if err := os.Chdir(dir); err != nil {
+		t.Fatalf("Chdir() error = %v", err)
+	}
+	t.Cleanup(func() { _ = os.Chdir(oldWD) })
+
+	svc, err := NewService(context.Background(), "testdb")
+	if err != nil {
+		t.Fatalf("NewService() error = %v", err)
+	}
+	t.Cleanup(func() { _ = svc.Close() })
+
+	inserted := svc.UpsertAnalyticItems(context.Background(), []AnalyticItem{{ID: 1}, {ID: 1}})
+	if inserted != 1 {
+		t.Fatalf("expected 1 new insert, got %d", inserted)
+	}
+
+	svc.SetCheckpoint(context.Background(), "bigquery", Checkpoint{ID: 10, Time: time.Unix(100, 0).UTC()})
+	cp, ok := svc.GetCheckpoint(context.Background(), "bigquery")
+	if !ok {
+		t.Fatal("expected checkpoint to exist")
+	}
+	if cp.ID != 10 {
+		t.Fatalf("expected checkpoint id 10, got %d", cp.ID)
+	}
+}