diff --git a/.github/workflows/tests_wasm.yaml b/.github/workflows/tests_wasm.yaml
new file mode 100644
index 000000000..43fcc1af4
--- /dev/null
+++ b/.github/workflows/tests_wasm.yaml
@@ -0,0 +1,42 @@
+---
+name: Tests WASM
+permissions: read-all
+on: [push, pull_request]
+jobs:
+  test-wasm-js:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - id: goversion
+        run: echo "goversion=$(cat .go-version)" >> "$GITHUB_OUTPUT"
+      - uses: actions/setup-go@d35c59abb061a4a6fb18e82ac0862c26744d6ab5 # v5.5.0
+        with:
+          go-version: ${{ steps.goversion.outputs.goversion }}
+      - name: Setup Node.js
+        uses: actions/setup-node@60edb5dd545a775178f52524783378180af0d1f8 # v4.0.2
+        with:
+          node-version: '20'
+      - name: Run WASM JS tests
+        run: |
+          env -i \
+            PATH="$PATH" \
+            HOME="$HOME" \
+            GOCACHE="$GOCACHE" \
+            GOPATH="$GOPATH" \
+            GOROOT="$(go env GOROOT)" \
+            make test-wasm
+
+  test-wasm-wasip1:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - id: goversion
+        run: echo "goversion=$(cat .go-version)" >> "$GITHUB_OUTPUT"
+      - uses: actions/setup-go@d35c59abb061a4a6fb18e82ac0862c26744d6ab5 # v5.5.0
+        with:
+          go-version: ${{ steps.goversion.outputs.goversion }}
+      - name: Install wazero
+        run: go install github.com/tetratelabs/wazero/cmd/wazero@latest
+      - name: Run WASM wasip1 tests
+        run: |
+          make test-wasip1
diff --git a/Makefile b/Makefile
index b1062cabe..5734b5d2a 100644
--- a/Makefile
+++ b/Makefile
@@ -51,6 +51,32 @@ test:
 	BBOLT_VERIFY=all TEST_FREELIST_TYPE=array go test -v ${TESTFLAGS} ./internal/...
 	BBOLT_VERIFY=all TEST_FREELIST_TYPE=array go test -v ${TESTFLAGS} ./cmd/bbolt/...
 
+.PHONY: test-wasm
+test-wasm:
+	@echo "WASM js test"
+	export PATH="$$PATH:$$(go env GOROOT)/lib/wasm" && \
+	GOOS=js GOARCH=wasm go test -v ${TESTFLAGS} -timeout ${TESTFLAGS_TIMEOUT}
+
+.PHONY: test-wasip1
+test-wasip1:
+	@echo "WASM wasip1 test"
+	if command -v wazero >/dev/null 2>&1; then \
+		echo "Using wazero runtime"; \
+		GOOS=wasip1 GOARCH=wasm go test -v ${TESTFLAGS} -timeout ${TESTFLAGS_TIMEOUT} \
+			-exec="wazero run -mount=$(shell mktemp -d):/tmp -mount=.:/test"; \
+	elif command -v wasmtime >/dev/null 2>&1; then \
+		WASI_TEMP=$$(mktemp -d); \
+		echo "Using wasmtime runtime with temp dir: $$WASI_TEMP"; \
+		GOOS=wasip1 GOARCH=wasm go test -v ${TESTFLAGS} -timeout ${TESTFLAGS_TIMEOUT} \
+			-exec="wasmtime --dir=. --dir=$$WASI_TEMP --env=TMPDIR=$$WASI_TEMP"; \
+	else \
+		echo "No WASI runtime found - install wazero (recommended) or wasmtime"; \
+		echo "  go install github.com/tetratelabs/wazero/cmd/wazero@latest"; \
+		echo "  brew install wasmtime"; \
+		echo "Building wasip1 binary to verify compilation..."; \
+		GOOS=wasip1 GOARCH=wasm go build .; \
+	fi
+
 .PHONY: coverage
 coverage:
 	@echo "hashmap freelist test"
diff --git a/bolt_unix.go b/bolt_unix.go
index f68e721f5..9c4aa4044 100644
--- a/bolt_unix.go
+++ b/bolt_unix.go
@@ -1,4 +1,4 @@
-//go:build !windows && !plan9 && !solaris && !aix && !android
+//go:build !windows && !plan9 && !solaris && !aix && !android && !js && !wasip1
 
 package bbolt
 
diff --git a/bolt_wasm.go b/bolt_wasm.go
new file mode 100644
index 000000000..d0a2ce83e
--- /dev/null
+++ b/bolt_wasm.go
@@ -0,0 +1,147 @@
+//go:build js || wasip1
+
+package bbolt
+
+import (
+	"fmt"
+	"io"
+	"time"
+	"unsafe"
+
+	berrors "go.etcd.io/bbolt/errors"
+	"go.etcd.io/bbolt/internal/common"
+)
+
+// mmap memory maps a DB's data file.
+func mmap(db *DB, sz int) error {
+	// Check MaxSize constraint for WASM platforms
+	if !db.readOnly && db.MaxSize > 0 && sz > db.MaxSize {
+		// The max size only limits future writes; however, we don't block opening
+		// and mapping the database if it already exceeds the limit.
+		fileSize, err := db.fileSize()
+		if err != nil {
+			return fmt.Errorf("could not check existing db file size: %s", err)
+		}
+
+		if sz > fileSize {
+			return berrors.ErrMaxSizeReached
+		}
+	}
+
+	// Truncate and fsync to ensure file size metadata is flushed.
+	// https://github.com/boltdb/bolt/issues/284
+	if !db.NoGrowSync && !db.readOnly {
+		if err := db.file.Truncate(int64(sz)); err != nil {
+			return fmt.Errorf("file resize error: %s", err)
+		}
+		if err := db.file.Sync(); err != nil {
+			return fmt.Errorf("file sync error: %s", err)
+		}
+	}
+
+	// Map the data file to memory.
+	b := make([]byte, sz)
+	if sz > 0 {
+		// Read the data file.
+		if _, err := db.file.ReadAt(b, 0); err != nil && err != io.EOF {
+			return err
+		}
+	}
+
+	// Save the original byte slice and convert to a byte array pointer.
+	db.dataref = b
+	db.datasz = sz
+	if sz > 0 {
+		db.data = (*[common.MaxMapSize]byte)(unsafe.Pointer(&b[0]))
+	}
+
+	return nil
+}
+
+// munmap unmaps a DB's data file from memory.
+func munmap(db *DB) error {
+	// In WASM, we just clear the references
+	db.dataref = nil
+	db.data = nil
+	db.datasz = 0
+	return nil
+}
+
+// madvise is not supported in WASM.
+func madvise(b []byte, advice int) error {
+	// Not implemented - no memory advice in WASM
+	return nil
+}
+
+// mlock is not supported in WASM.
+func mlock(db *DB, fileSize int) error {
+	// Not implemented - no memory locking in WASM
+	return nil
+}
+
+// munlock is not supported in WASM.
+func munlock(db *DB, fileSize int) error {
+	// Not implemented - no memory unlocking in WASM
+	return nil
+}
+
+// flock acquires an advisory lock on a file descriptor.
+func flock(db *DB, exclusive bool, timeout time.Duration) error {
+	// Not implemented - no file locking in WASM
+	return nil
+}
+
+// funlock releases an advisory lock on a file descriptor.
+func funlock(db *DB) error {
+	// Not implemented - no file unlocking in WASM
+	return nil
+}
+
+// fdatasync flushes written data to a file descriptor.
+func fdatasync(db *DB) error {
+	if db.file == nil {
+		return nil
+	}
+	return db.file.Sync()
+}
+
+// txInit refreshes the memory buffer from the file for WASM platforms.
+// This is needed because WASM doesn't have real mmap, so we need to manually
+// sync the memory buffer with the file to see changes from previous transactions.
+func (db *DB) txInit() error {
+	// For read-only databases or initial state, skip refresh
+	if db.file == nil {
+		return nil
+	}
+
+	// Check if the file has grown
+	fileInfo, err := db.file.Stat()
+	if err != nil {
+		return err
+	}
+	fileSize := int(fileInfo.Size())
+
+	// If file has grown or we need to initialize, refresh memory
+	if fileSize > db.datasz || db.datasz == 0 {
+		// Re-mmap with the new size
+		if err := mmap(db, fileSize); err != nil {
+			return err
+		}
+	} else if db.datasz > 0 {
+		// Refresh the existing buffer
+		b := make([]byte, db.datasz)
+		if _, err := db.file.ReadAt(b, 0); err != nil && err != io.EOF {
+			return err
+		}
+		db.dataref = b
+		db.data = (*[common.MaxMapSize]byte)(unsafe.Pointer(&b[0]))
+	}
+
+	// Update meta page pointers
+	if db.pageSize > 0 && db.datasz >= db.pageSize*2 {
+		db.meta0 = db.page(0).Meta()
+		db.meta1 = db.page(1).Meta()
+	}
+
+	return nil
+}
diff --git a/boltsync_unix.go b/boltsync_unix.go
index 27face752..77266173b 100644
--- a/boltsync_unix.go
+++ b/boltsync_unix.go
@@ -1,4 +1,4 @@
-//go:build !windows && !plan9 && !linux && !openbsd
+//go:build !windows && !plan9 && !linux && !openbsd && !js && !wasip1
 
 package bbolt
 
diff --git a/bucket_test.go b/bucket_test.go
index 493d133a7..533222c65 100644
--- a/bucket_test.go
+++ b/bucket_test.go
@@ -8,6 +8,7 @@ import (
 	"log"
 	"math/rand"
 	"os"
+	"runtime"
 	"strconv"
 	"strings"
 	"testing"
@@ -208,6 +209,9 @@ func TestDB_Put_VeryLarge(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
+		t.Skip("skipping test on WASM due to memory constraints")
+	}
 
 	n, batchN := 400000, 200000
 	ksize, vsize := 8, 500
@@ -377,6 +381,9 @@ func TestBucket_Delete_FreelistOverflow(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
+		t.Skip("skipping test on WASM due to memory constraints")
+	}
 
 	db := btesting.MustCreateDB(t)
 
@@ -1207,6 +1214,9 @@ func TestBucket_Put_KeyTooLarge(t *testing.T) {
 
 // Ensure that an error is returned when inserting a value that's too large.
 func TestBucket_Put_ValueTooLarge(t *testing.T) {
+	if runtime.GOARCH == "wasm" {
+		t.Skip("skipping test on wasm")
+	}
 	// Skip this test on DroneCI because the machine is resource constrained.
 	if os.Getenv("DRONE") == "true" {
 		t.Skip("not enough RAM for test")
diff --git a/db.go b/db.go
index 5d3e26496..acbbd6286 100644
--- a/db.go
+++ b/db.go
@@ -772,12 +772,28 @@ func (db *DB) Logger() Logger {
 	return db.logger
 }
 
+// txIniter is an interface that allows for platform-specific transaction
+// initialization.
+type txIniter interface {
+	txInit() error
+}
+
 func (db *DB) beginTx() (*Tx, error) {
 	// Lock the meta pages while we initialize the transaction. We obtain
 	// the meta lock before the mmap lock because that's the order that the
 	// write transaction will obtain them.
 	db.metalock.Lock()
 
+	// Allow WASM-specific transaction initialization
+	if runtime.GOARCH == "wasm" {
+		if initer, ok := any(db).(txIniter); ok {
+			if err := initer.txInit(); err != nil {
+				db.metalock.Unlock()
+				return nil, err
+			}
+		}
+	}
+
 	// Obtain a read-only lock on the mmap. When the mmap is remapped it will
 	// obtain a write lock so all transactions must finish before it can be
 	// remapped.
@@ -834,6 +850,16 @@ func (db *DB) beginRWTx() (*Tx, error) {
 	db.metalock.Lock()
 	defer db.metalock.Unlock()
 
+	// Allow WASM-specific transaction initialization
+	if runtime.GOARCH == "wasm" {
+		if initer, ok := any(db).(txIniter); ok {
+			if err := initer.txInit(); err != nil {
+				db.rwlock.Unlock()
+				return nil, err
+			}
+		}
+	}
+
 	// Exit if the database is not open yet.
 	if !db.opened {
 		db.rwlock.Unlock()
diff --git a/db_test.go b/db_test.go
index feb3368ce..dc2c05a13 100644
--- a/db_test.go
+++ b/db_test.go
@@ -247,6 +247,9 @@ func TestOpen_ReadPageSize_FromMeta1_OS(t *testing.T) {
 // Ensure that it can read the page size from the second meta page if the first one is invalid.
 // The page size is expected to be the given page size in this case.
 func TestOpen_ReadPageSize_FromMeta1_Given(t *testing.T) {
+	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
+		t.Skip("skipping test on WASM due to memory constraints")
+	}
 	// test page size from 1KB (1024<<0) to 16MB(1024<<14)
 	for i := 0; i <= 14; i++ {
 		givenPageSize := 1024 << uint(i)
@@ -332,6 +335,9 @@ func TestOpen_Size_Large(t *testing.T) {
 	if testing.Short() {
 		t.Skip("short mode")
 	}
+	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
+		t.Skip("skipping large file test in WASM")
+	}
 
 	// Open a data file.
 	db := btesting.MustCreateDB(t)
@@ -456,6 +462,10 @@ func TestOpen_FileTooSmall(t *testing.T) {
 // read transaction blocks the write transaction and causes deadlock.
 // This is a very hacky test since the mmap size is not exposed.
 func TestDB_Open_InitialMmapSize(t *testing.T) {
+	t.Parallel()
+	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" {
+		t.Skip("skipping test on WASM due to memory constraints")
+	}
 	path := tempfile()
 	defer os.Remove(path)
 
diff --git a/internal/common/bolt_wasm.go b/internal/common/bolt_wasm.go
new file mode 100644
index 000000000..d7ab938cb
--- /dev/null
+++ b/internal/common/bolt_wasm.go
@@ -0,0 +1,9 @@
+//go:build js || wasip1
+
+package common
+
+// MaxMapSize represents the largest mmap size supported by Bolt.
+const MaxMapSize = 0x10000000
+
+// MaxAllocSize is the size used when creating array pointers.
+const MaxAllocSize = 0x10100000
diff --git a/mlock_unix.go b/mlock_unix.go
index 9a0fd332c..80c36fa1d 100644
--- a/mlock_unix.go
+++ b/mlock_unix.go
@@ -1,4 +1,4 @@
-//go:build !windows
+//go:build !windows && !js && !wasip1
 
 package bbolt
 
diff --git a/simulation_test.go b/simulation_test.go
index 6f4d5b236..48ed99414 100644
--- a/simulation_test.go
+++ b/simulation_test.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"math/rand"
+	"runtime"
 	"sync"
 	"sync/atomic"
 	"testing"
@@ -34,6 +35,9 @@ func testSimulate(t *testing.T, openOption *bolt.Options, round, threadCount, pa
 	if testing.Short() {
 		t.Skip("skipping test in short mode.")
 	}
+	if runtime.GOARCH == "wasm" && threadCount >= 1000 {
+		t.Skip("skipping test on wasm with 1000+ concurrency")
+	}
 
 	// A list of operations that readers and writers can perform.
 	var readerHandlers = []simulateHandler{simulateGetHandler}
diff --git a/unix_test.go b/unix_test.go
index ac53ad559..ccb18201d 100644
--- a/unix_test.go
+++ b/unix_test.go
@@ -1,4 +1,4 @@
-//go:build !windows
+//go:build !windows && !js && !wasip1
 
 package bbolt_test