diff --git a/bench/snippets/buffer-to-string.mjs b/bench/snippets/buffer-to-string.mjs
index f4a1695725..c4dac62081 100644
--- a/bench/snippets/buffer-to-string.mjs
+++ b/bench/snippets/buffer-to-string.mjs
@@ -14,6 +14,14 @@ bench(`Buffer(${uuid.byteLength}).toString('base64')`, () => {
   return uuid.toString("base64");
 });
 
+bench(`Buffer(${bigBuffer.byteLength}).toString('base64url')`, () => {
+  return bigBuffer.toString("base64url");
+});
+
+bench(`Buffer(${uuid.byteLength}).toString('base64url')`, () => {
+  return uuid.toString("base64url");
+});
+
 bench(`Buffer(${bigBuffer.byteLength}).toString('hex')`, () => {
   return bigBuffer.toString("hex");
 });
diff --git a/src/bun.js/bindings/wtf-bindings.cpp b/src/bun.js/bindings/wtf-bindings.cpp
index de9a6ef55c..5bb26fbe55 100644
--- a/src/bun.js/bindings/wtf-bindings.cpp
+++ b/src/bun.js/bindings/wtf-bindings.cpp
@@ -5,6 +5,7 @@
 #include <wtf/dtoa.h>
 #include <atomic>
 
+#include "simdutf.h"
 #if OS(WINDOWS)
 #include <uv.h>
 #endif
@@ -170,57 +171,20 @@ extern "C" int Bun__ttySetMode(int fd, int mode)
 
 extern "C" double WTF__parseDouble(const LChar* string, size_t length, size_t* position)
 {
-    return WTF::parseDouble({string, length}, *position);
+    return WTF::parseDouble({ string, length }, *position);
 }
 
 extern "C" void WTF__copyLCharsFromUCharSource(LChar* destination, const UChar* source, size_t length)
 {
-    WTF::StringImpl::copyCharacters(destination, {source, length});
+    WTF::StringImpl::copyCharacters(destination, { source, length });
 }
 
-// For whatever reason
-// Doing this in C++/C is 2x faster than doing it in Zig.
-// However, it's still slower than it should be.
-static constexpr size_t encodeMapSize = 64;
-static constexpr char base64URLEncMap[encodeMapSize] = {
-    0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B,
-    0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56,
-    0x57, 0x58, 0x59, 0x5A, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
-    0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72,
-    0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x30, 0x31, 0x32,
-    0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x2D, 0x5F
-};
-
-extern "C" size_t WTF__base64URLEncode(const unsigned char* __restrict inputDataBuffer, size_t inputDataBufferSize,
-    unsigned char* __restrict destinationDataBuffer,
+extern "C" size_t WTF__base64URLEncode(const char* __restrict inputDataBuffer, size_t inputDataBufferSize,
+    char* __restrict destinationDataBuffer,
     size_t destinationDataBufferSize)
 {
-    size_t sidx = 0;
-    size_t didx = 0;
-
-    if (inputDataBufferSize > 1) {
-        while (sidx < inputDataBufferSize - 2) {
-            destinationDataBuffer[didx++] = base64URLEncMap[(inputDataBuffer[sidx] >> 2) & 077];
-            destinationDataBuffer[didx++] = base64URLEncMap[((inputDataBuffer[sidx + 1] >> 4) & 017) | ((inputDataBuffer[sidx] << 4) & 077)];
-            destinationDataBuffer[didx++] = base64URLEncMap[((inputDataBuffer[sidx + 2] >> 6) & 003) | ((inputDataBuffer[sidx + 1] << 2) & 077)];
-            destinationDataBuffer[didx++] = base64URLEncMap[inputDataBuffer[sidx + 2] & 077];
-            sidx += 3;
-        }
-    }
-
-    if (sidx < inputDataBufferSize) {
-        destinationDataBuffer[didx++] = base64URLEncMap[(inputDataBuffer[sidx] >> 2) & 077];
-        if (sidx < inputDataBufferSize - 1) {
-            destinationDataBuffer[didx++] = base64URLEncMap[((inputDataBuffer[sidx + 1] >> 4) & 017) | ((inputDataBuffer[sidx] << 4) & 077)];
-            destinationDataBuffer[didx++] = base64URLEncMap[(inputDataBuffer[sidx + 1] << 2) & 077];
-        } else
-            destinationDataBuffer[didx++] = base64URLEncMap[(inputDataBuffer[sidx] << 4) & 077];
-    }
-
-    while (didx < destinationDataBufferSize)
-        destinationDataBuffer[didx++] = '=';
-
-    return destinationDataBufferSize;
+    UNUSED_PARAM(destinationDataBufferSize);
+    return simdutf::binary_to_base64(inputDataBuffer, inputDataBufferSize, destinationDataBuffer, simdutf::base64_url);
 }
 
 namespace Bun {
@@ -237,8 +201,10 @@ String base64URLEncodeToString(Vector<uint8_t> data)
         RELEASE_ASSERT_NOT_REACHED();
         return String();
     }
-    encodedLength = WTF__base64URLEncode(data.data(), data.size(), ptr, encodedLength);
-    RELEASE_ASSERT(result.length() == encodedLength);
+    encodedLength = WTF__base64URLEncode(reinterpret_cast<const char*>(data.data()), data.size(), reinterpret_cast<char*>(ptr), encodedLength);
+    if (result.length() != encodedLength) {
+        return result.substringSharingImpl(0, encodedLength);
+    }
     return result;
 }