diff --git a/go/svc/invoice/model.go b/go/svc/invoice/model.go
new file mode 100644
index 0000000..0ed8245
--- /dev/null
+++ b/go/svc/invoice/model.go
@@ -0,0 +1,213 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strconv"
+
+	"github.com/golang/glog"
+	"github.com/golang/protobuf/proto"
+	_ "github.com/mattn/go-sqlite3"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	pb "code.hackerspace.pl/hscloud/proto/invoice"
+)
+
+type model struct {
+	db *sql.DB
+}
+
+func newModel(dsn string) (*model, error) {
+	db, err := sql.Open("sqlite3", dsn)
+	if err != nil {
+		return nil, err
+	}
+	return &model{
+		db: db,
+	}, nil
+}
+
+func (m *model) init() error {
+	_, err := m.db.Exec(`
+		create table invoice (
+			id integer primary key not null,
+			proto blob not null
+		);
+		create table invoice_seal (
+			id integer primary key not null,
+			invoice_id integer not null,
+			final_uid text not null unique,
+			foreign key (invoice_id) references invoice(id)
+		);
+		create table invoice_blob (
+			id integer primary key not null,
+			invoice_id integer not null,
+			pdf blob not null,
+			foreign key (invoice_id) references invoice(id)
+		);
+	`)
+	return err
+}
+
+func (m *model) sealInvoice(ctx context.Context, uid string) error {
+	id, err := strconv.Atoi(uid)
+	if err != nil {
+		return status.Error(codes.InvalidArgument, "invalid uid")
+	}
+
+	invoice, err := m.getInvoice(ctx, uid)
+	if err != nil {
+		return err
+	}
+
+	tx, err := m.db.BeginTx(ctx, nil)
+	if err != nil {
+		return err
+	}
+
+	q := `
+		insert into invoice_seal (
+			invoice_id, final_uid
+		) values (
+			?,
+			( select printf("%04d", ifnull( (select final_uid as v from invoice_seal order by final_uid desc limit 1), 19000) + 1 ))
+		)
+
+	`
+	res, err := tx.Exec(q, id)
+	if err != nil {
+		return err
+	}
+
+	lastInvoiceSealId, err := res.LastInsertId()
+	if err != nil {
+		return err
+	}
+
+	q = `
+		select final_uid from invoice_seal where id = ?
+	`
+
+	var finalUid string
+	if err := tx.QueryRow(q, lastInvoiceSealId).Scan(&finalUid); err != nil {
+		return err
+	}
+
+	q = `
+		insert into invoice_blob (
+			invoice_id, pdf
+		) values (
+			?,
+			?
+		)
+	`
+
+	pdfBlob, err := renderInvoicePDF(invoice, finalUid, false)
+	if err != nil {
+		return err
+	}
+
+	if _, err := tx.Exec(q, id, pdfBlob); err != nil {
+		return err
+	}
+
+	if err := tx.Commit(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (m *model) createInvoice(ctx context.Context, i *pb.Invoice) (string, error) {
+	data, err := proto.Marshal(i)
+	if err != nil {
+		return "", err
+	}
+
+	sql := `
+		insert into invoice (
+			proto
+		) values (
+			?
+		)
+	`
+	res, err := m.db.Exec(sql, data)
+	if err != nil {
+		return "", err
+	}
+	id, err := res.LastInsertId()
+	if err != nil {
+		return "", err
+	}
+
+	glog.Infof("%+v", id)
+	return fmt.Sprintf("%d", id), nil
+}
+
+func (m *model) getRendered(ctx context.Context, uid string) ([]byte, error) {
+	id, err := strconv.Atoi(uid)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, "invalid uid")
+	}
+
+	q := `
+		select invoice_blob.pdf from invoice_blob where invoice_blob.invoice_id = ?
+	`
+	res := m.db.QueryRow(q, id)
+
+	data := []byte{}
+	if err := res.Scan(&data); err != nil {
+		if err == sql.ErrNoRows {
+			return nil, status.Error(codes.InvalidArgument, "no such invoice")
+		}
+		return nil, err
+	}
+	return data, nil
+}
+
+func (m *model) getSealedUid(ctx context.Context, uid string) (string, error) {
+	id, err := strconv.Atoi(uid)
+	if err != nil {
+		return "", status.Error(codes.InvalidArgument, "invalid uid")
+	}
+
+	q := `
+		select invoice_seal.final_uid from invoice_seal where invoice_seal.invoice_id = ?
+	`
+	res := m.db.QueryRow(q, id)
+	finalUid := ""
+	if err := res.Scan(&finalUid); err != nil {
+		if err == sql.ErrNoRows {
+			return "", nil
+		}
+		return "", err
+	}
+	return finalUid, nil
+}
+
+func (m *model) getInvoice(ctx context.Context, uid string) (*pb.Invoice, error) {
+	id, err := strconv.Atoi(uid)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, "invalid uid")
+	}
+
+	q := `
+		select invoice.proto from invoice where invoice.id = ?
+	`
+	res := m.db.QueryRow(q, id)
+	data := []byte{}
+	if err := res.Scan(&data); err != nil {
+		if err == sql.ErrNoRows {
+			return nil, status.Error(codes.NotFound, "no such invoice")
+		}
+		return nil, err
+	}
+
+	p := &pb.Invoice{}
+	if err := proto.Unmarshal(data, p); err != nil {
+		return nil, err
+	}
+	return p, nil
+}