diff --git a/gsfa/gsfa-read-multiepoch.go b/gsfa/gsfa-read-multiepoch.go
index 6646136a..c1218068 100644
--- a/gsfa/gsfa-read-multiepoch.go
+++ b/gsfa/gsfa-read-multiepoch.go
@@ -10,6 +10,7 @@ import (
 	"github.com/rpcpool/yellowstone-faithful/compactindexsized"
 	"github.com/rpcpool/yellowstone-faithful/gsfa/linkedlog"
 	"github.com/rpcpool/yellowstone-faithful/ipld/ipldbindcode"
+	"github.com/rpcpool/yellowstone-faithful/slottools"
 	"k8s.io/klog/v2"
 )
 
@@ -200,3 +201,101 @@ epochLoop:
 	}
 	return transactions, nil
 }
+
+func (multi *GsfaReaderMultiepoch) GetBeforeUntilSlot(
+	ctx context.Context,
+	pk solana.PublicKey,
+	limit int,
+	before uint64, // Before this slot, exclusive (i.e. get slots older than this slot, excluding it).
+	until uint64, // Until this slot, inclusive (i.e. stop at this slot, including it).
+	fetcher func(uint64, linkedlog.OffsetAndSizeAndSlot) (*ipldbindcode.Transaction, error),
+) (EpochToTransactionObjects, error) {
+	if limit <= 0 {
+		return make(EpochToTransactionObjects), nil
+	}
+	return multi.iterBeforeUntilSlot(ctx, pk, limit, before, until, fetcher)
+}
+
+// GetBeforeUntilSlot gets the signatures for the given public key,
+// before the given slot.
+func (multi *GsfaReaderMultiepoch) iterBeforeUntilSlot(
+	ctx context.Context,
+	pk solana.PublicKey,
+	limit int,
+	before uint64, // Before this slot, exclusive (i.e. get slots older than this slot, excluding it).
+	until uint64, // Until this slot, inclusive (i.e. stop at this slot, including it).
+	fetcher func(uint64, linkedlog.OffsetAndSizeAndSlot) (*ipldbindcode.Transaction, error),
+) (EpochToTransactionObjects, error) {
+	if limit <= 0 || before < until {
+		return make(EpochToTransactionObjects), nil
+	}
+
+	transactions := make(EpochToTransactionObjects)
+	beforeEpoch := slottools.CalcEpochForSlot(before)
+
+epochLoop:
+	for readerIndex, index := range multi.epochs {
+		if ctx.Err() != nil {
+			return nil, ctx.Err()
+		}
+		epochNum, ok := index.GetEpoch()
+		if !ok {
+			return nil, fmt.Errorf("epoch is not set for the #%d provided gsfa reader", readerIndex)
+		}
+		if epochNum > beforeEpoch {
+			continue epochLoop
+		}
+
+		locsStartedAt := time.Now()
+		locs, err := index.offsets.Get(pk)
+		if err != nil {
+			if compactindexsized.IsNotFound(err) {
+				continue epochLoop
+			}
+			return nil, fmt.Errorf("error while getting initial offset: %w", err)
+		}
+		klog.V(5).Infof("locs.OffsetToFirst took %s", time.Since(locsStartedAt))
+		debugln("locs.OffsetToFirst:", locs)
+
+		next := locs // Start from the latest, and go back in time.
+
+		for {
+			if next == nil || next.IsZero() { // no previous.
+				continue epochLoop
+			}
+			if limit > 0 && transactions.Count() >= limit {
+				break epochLoop
+			}
+			startedReadAt := time.Now()
+			locations, newNext, err := index.ll.ReadWithSize(next.Offset, next.Size)
+			if err != nil {
+				return nil, fmt.Errorf("error while reading linked log with next=%v: %w", next, err)
+			}
+			klog.V(5).Infof("ReadWithSize took %s to get %d locs", time.Since(startedReadAt), len(locations))
+			if len(locations) == 0 {
+				continue epochLoop
+			}
+			debugln("sigIndexes:", locations, "newNext:", newNext)
+			next = &newNext
+			for locIndex, txLoc := range locations {
+				tx, err := fetcher(epochNum, txLoc)
+				if err != nil {
+					return nil, fmt.Errorf("error while getting signature at index=%v: %w", txLoc, err)
+				}
+				if tx.Slot < int(until) {
+					break epochLoop
+				}
+				sig, err := tx.Signature()
+				if err != nil {
+					return nil, fmt.Errorf("error while getting signature: %w", err)
+				}
+				klog.V(5).Infoln(locIndex, "sig:", sig, "epoch:", epochNum)
+				if limit > 0 && transactions.Count() >= limit {
+					break epochLoop
+				}
+				transactions[epochNum] = append(transactions[epochNum], tx)
+			}
+		}
+	}
+	return transactions, nil
+}