grpc · brzosthub · Aug 11, 2026
diff --git a/packages/proto-loader/README.md b/packages/proto-loader/README.md
@@ -31,7 +31,7 @@ The options parameter is an object that can have the following optional properti
 | Field name | Valid values | Description
 |------------|--------------|------------
 | `keepCase` | `true` or `false` | Preserve field names. The default is to change them to camel case.
-| `longs` | `String` or `Number` | The type to use to represent `long` values. Defaults to a `Long` object type.
+| `longs` | `String`, `Number`, or `BigInt` | The type to use to represent `long` values. Defaults to a `Long` object type. Requires `protobufjs` >= 7.6.0 when using `BigInt`.
 | `enums` | `String` | The type to use to represent `enum` values. Defaults to the numeric value.
 | `bytes` | `Array` or `String` | The type to use to represent `bytes` values. Defaults to `Buffer`.
 | `defaults` | `true` or `false` | Set default values on output objects. Defaults to `false`.
@@ -66,7 +66,7 @@ Options:
       --keepCase             Preserve the case of field names
                                                       [boolean] [default: false]
       --longs                The type that should be used to output 64 bit
-                             integer values. Can be String, Number
+                             integer values. Can be String, Number, BigInt
                                                       [string] [default: "Long"]
       --enums                The type that should be used to output enum fields.
                              Can be String          [string] [default: "number"]

diff --git a/packages/proto-loader/bin/proto-loader-gen-types.ts b/packages/proto-loader/bin/proto-loader-gen-types.ts
@@ -214,7 +214,7 @@ function getTypeNamePermissive(fieldType: string, resolvedType: Protobuf.Type |
     case 'sint64':
     case 'fixed64':
     case 'sfixed64':
-      return 'number | string | Long';
+      return 'number | string | Long | bigint';
     case 'bool':
       return 'boolean';
     case 'string':
@@ -312,6 +312,8 @@ function getTypeNameRestricted(fieldType: string, resolvedType: Protobuf.Type |
         return 'number';
       } else if (options.longs === String) {
         return 'string';
+      } else if (options.longs === BigInt) {
+        return 'bigint';
       } else {
         return 'Long';
       }
@@ -887,6 +889,7 @@ async function runScript() {
       switch (value) {
         case 'String': return String;
         case 'Number': return Number;
+        case 'BigInt': return BigInt;
         default: return undefined;
       }
     }).coerce('enums', value => {
@@ -906,7 +909,7 @@ async function runScript() {
       verbose: 'v'
     }).describe({
       keepCase: 'Preserve the case of field names',
-      longs: 'The type that should be used to output 64 bit integer values. Can be String, Number',
+      longs: 'The type that should be used to output 64 bit integer values. Can be String, Number, BigInt',
       enums: 'The type that should be used to output enum fields. Can be String',
       bytes: 'The type that should be used to output bytes fields. Can be String, Array',
       defaults: 'Output default values for omitted fields',

diff --git a/packages/proto-loader/golden-generated/google/protobuf/Duration.ts b/packages/proto-loader/golden-generated/google/protobuf/Duration.ts
@@ -3,7 +3,7 @@
 import type { Long } from '@grpc/proto-loader';
 
 export interface IDuration {
-  'seconds'?: (number | string | Long);
+  'seconds'?: (number | string | Long | bigint);
   'nanos'?: (number);
 }
 

diff --git a/packages/proto-loader/golden-generated/google/protobuf/Timestamp.ts b/packages/proto-loader/golden-generated/google/protobuf/Timestamp.ts
@@ -3,7 +3,7 @@
 import type { Long } from '@grpc/proto-loader';
 
 export interface ITimestamp {
-  'seconds'?: (number | string | Long);
+  'seconds'?: (number | string | Long | bigint);
   'nanos'?: (number);
 }
 

diff --git a/packages/proto-loader/golden-generated/google/protobuf/UninterpretedOption.ts b/packages/proto-loader/golden-generated/google/protobuf/UninterpretedOption.ts
@@ -15,8 +15,8 @@ export interface O_google_protobuf_UninterpretedOption_NamePart {
 export interface IUninterpretedOption {
   'name'?: (I_google_protobuf_UninterpretedOption_NamePart)[];
   'identifierValue'?: (string);
-  'positiveIntValue'?: (number | string | Long);
-  'negativeIntValue'?: (number | string | Long);
+  'positiveIntValue'?: (number | string | Long | bigint);
+  'negativeIntValue'?: (number | string | Long | bigint);
   'doubleValue'?: (number | string);
   'stringValue'?: (Buffer | Uint8Array | string);
   'aggregateValue'?: (string);

diff --git a/packages/proto-loader/package.json b/packages/proto-loader/package.json
@@ -47,7 +47,7 @@
   "dependencies": {
     "lodash.camelcase": "^4.3.0",
     "long": "^5.0.0",
-    "protobufjs": "^7.5.5",
+    "protobufjs": "^7.6.0",
     "yargs": "^17.7.2"
   },
   "devDependencies": {

diff --git a/packages/proto-loader/src/index.ts b/packages/proto-loader/src/index.ts
@@ -412,8 +412,8 @@ function createPackageDefinitionFromDescriptorSet(
  * @param options.keepCase Preserve field names. The default is to change them
  *     to camel case.
  * @param options.longs The type that should be used to represent `long` values.
- *     Valid options are `Number` and `String`. Defaults to a `Long` object type
- *     from a library.
+ *     Valid options are `Number`, `String`, and `BigInt`. Defaults to a `Long`
+ *     object type from a library.
  * @param options.enums The type that should be used to represent `enum` values.
  *     The only valid option is `String`. Defaults to the numeric value.
  * @param options.bytes The type that should be used to represent `bytes`

diff --git a/packages/proto-loader/test/descriptor_type_test.ts b/packages/proto-loader/test/descriptor_type_test.ts
@@ -178,4 +178,47 @@ describe('Descriptor types', () => {
       },
     })
   })
+
+  it('Can deserialize int64 values as BigInt', () => {
+    const wideValue = '9223372036854775807';
+    const encodedDef = proto_loader.loadSync(
+      `${TEST_PROTO_DIR}/messages.proto`,
+      { keepCase: true }
+    ).LongValues;
+    assert(isTypeObject(encodedDef));
+    const longValuesDef = encodedDef as proto_loader.MessageTypeDefinition<
+      object,
+      object
+    >;
+    const encoded = longValuesDef.serialize({
+      int_64: wideValue,
+      uint_64: wideValue,
+      sint_64: wideValue,
+      fixed_64: wideValue,
+      sfixed_64: wideValue,
+    });
+    const decodedDef = proto_loader.loadSync(
+      `${TEST_PROTO_DIR}/messages.proto`,
+      {
+        keepCase: true,
+        longs: BigInt,
+      }
+    ).LongValues;
+    assert(isTypeObject(decodedDef));
+    const decoded = (
+      decodedDef as proto_loader.MessageTypeDefinition<object, object>
+    ).deserialize(encoded) as {
+      int_64: bigint;
+      uint_64: bigint;
+      sint_64: bigint;
+      fixed_64: bigint;
+      sfixed_64: bigint;
+    };
+    assert.strictEqual(typeof decoded.int_64, 'bigint');
+    assert.strictEqual(decoded.int_64, BigInt(wideValue));
+    assert.strictEqual(decoded.uint_64, BigInt(wideValue));
+    assert.strictEqual(decoded.sint_64, BigInt(wideValue));
+    assert.strictEqual(decoded.fixed_64, BigInt(wideValue));
+    assert.strictEqual(decoded.sfixed_64, BigInt(wideValue));
+  });
 });
diff --git a/packages/proto-loader/tsconfig.json b/packages/proto-loader/tsconfig.json
@@ -3,7 +3,7 @@
   "compilerOptions": {
     "rootDir": ".",
     "outDir": "build",
-    "lib": ["es2017"],
+    "lib": ["es2017", "ES2020.BigInt"],
     "target": "es2017"
   },
   "include": [