diff --git a/packages/eslint-config-sdk/src/index.js b/packages/eslint-config-sdk/src/index.js
index 2b67173f403d..b4e7de5f211f 100644
--- a/packages/eslint-config-sdk/src/index.js
+++ b/packages/eslint-config-sdk/src/index.js
@@ -39,6 +39,10 @@ module.exports = {
         // Enforce type annotations to maintain consistency. This is especially important as
         // we have a public API, so we want changes to be very explicit.
         '@typescript-eslint/typedef': ['error', { arrowParameter: false }],
+
+        // Although for most codebases inferencing the return type is fine, we explicitly ask to annotate
+        // all functions with a return type. This is so that intent is as clear as possible. We are guarding against
+        // cases where you accidently refactor a function's return type to be the wrong type.
         '@typescript-eslint/explicit-function-return-type': ['error', { allowExpressions: true }],
 
         // Consistent ordering of fields, methods and constructors for classes should be enforced
diff --git a/packages/tracing/src/browser/metrics.ts b/packages/tracing/src/browser/metrics.ts
index 96ff9ed0b9e3..0e3fa26d7fea 100644
--- a/packages/tracing/src/browser/metrics.ts
+++ b/packages/tracing/src/browser/metrics.ts
@@ -1,3 +1,4 @@
+/* eslint-disable max-lines */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import { SpanContext } from '@sentry/types';
 import { getGlobalObject, logger } from '@sentry/utils';
@@ -211,10 +212,17 @@ function addMeasureSpans(
   return measureStartTimestamp;
 }
 
+export interface ResourceEntry extends Record<string, unknown> {
+  initiatorType?: string;
+  transferSize?: number;
+  encodedBodySize?: number;
+  decodedBodySize?: number;
+}
+
 /** Create resource related spans */
-function addResourceSpans(
+export function addResourceSpans(
   transaction: Transaction,
-  entry: Record<string, any>,
+  entry: ResourceEntry,
   resourceName: string,
   startTime: number,
   duration: number,
@@ -226,14 +234,26 @@ function addResourceSpans(
     return undefined;
   }
 
+  const data: Record<string, any> = {};
+  if ('transferSize' in entry) {
+    data['Transfer Size'] = entry.transferSize;
+  }
+  if ('encodedBodySize' in entry) {
+    data['Encoded Body Size'] = entry.encodedBodySize;
+  }
+  if ('decodedBodySize' in entry) {
+    data['Decoded Body Size'] = entry.decodedBodySize;
+  }
+
   const startTimestamp = timeOrigin + startTime;
   const endTimestamp = startTimestamp + duration;
 
   _startChild(transaction, {
-    description: `${entry.initiatorType} ${resourceName}`,
+    description: resourceName,
     endTimestamp,
-    op: 'resource',
+    op: entry.initiatorType ? `resource.${entry.initiatorType}` : 'resource',
     startTimestamp,
+    data,
   });
 
   return endTimestamp;
diff --git a/packages/tracing/test/browser/metrics.test.ts b/packages/tracing/test/browser/metrics.test.ts
index bc4d3f6ee06d..f267e2e442dc 100644
--- a/packages/tracing/test/browser/metrics.test.ts
+++ b/packages/tracing/test/browser/metrics.test.ts
@@ -1,5 +1,5 @@
 import { Span, Transaction } from '../../src';
-import { _startChild } from '../../src/browser/metrics';
+import { _startChild, addResourceSpans, ResourceEntry } from '../../src/browser/metrics';
 
 describe('_startChild()', () => {
   it('creates a span with given properties', () => {
@@ -38,3 +38,132 @@ describe('_startChild()', () => {
     expect(transaction.startTimestamp).toEqual(123);
   });
 });
+
+describe('addResourceSpans', () => {
+  const transaction = new Transaction({ name: 'hello' });
+  beforeEach(() => {
+    transaction.startChild = jest.fn();
+  });
+
+  // We already track xhr, we don't need to use
+  it('does not create spans for xmlhttprequest', () => {
+    const entry: ResourceEntry = {
+      initiatorType: 'xmlhttprequest',
+      transferSize: 256,
+      encodedBodySize: 256,
+      decodedBodySize: 256,
+    };
+    addResourceSpans(transaction, entry, '/assets/to/me', 123, 456, 100);
+
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    expect(transaction.startChild).toHaveBeenCalledTimes(0);
+  });
+
+  it('does not create spans for fetch', () => {
+    const entry: ResourceEntry = {
+      initiatorType: 'fetch',
+      transferSize: 256,
+      encodedBodySize: 256,
+      decodedBodySize: 256,
+    };
+    addResourceSpans(transaction, entry, '/assets/to/me', 123, 456, 100);
+
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    expect(transaction.startChild).toHaveBeenCalledTimes(0);
+  });
+
+  it('creates spans for resource spans', () => {
+    const entry: ResourceEntry = {
+      initiatorType: 'css',
+      transferSize: 256,
+      encodedBodySize: 456,
+      decodedBodySize: 593,
+    };
+
+    const timeOrigin = 100;
+    const startTime = 23;
+    const duration = 356;
+
+    const endTimestamp = addResourceSpans(transaction, entry, '/assets/to/css', startTime, duration, timeOrigin);
+
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    expect(transaction.startChild).toHaveBeenCalledTimes(1);
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    expect(transaction.startChild).toHaveBeenLastCalledWith({
+      data: {
+        ['Decoded Body Size']: entry.decodedBodySize,
+        ['Encoded Body Size']: entry.encodedBodySize,
+        ['Transfer Size']: entry.transferSize,
+      },
+      description: '/assets/to/css',
+      endTimestamp: timeOrigin + startTime + duration,
+      op: 'resource.css',
+      startTimestamp: timeOrigin + startTime,
+    });
+
+    expect(endTimestamp).toBe(timeOrigin + startTime + duration);
+  });
+
+  it('creates a variety of resource spans', () => {
+    const table = [
+      {
+        initiatorType: undefined,
+        op: 'resource',
+      },
+      {
+        initiatorType: '',
+        op: 'resource',
+      },
+      {
+        initiatorType: 'css',
+        op: 'resource.css',
+      },
+      {
+        initiatorType: 'image',
+        op: 'resource.image',
+      },
+      {
+        initiatorType: 'script',
+        op: 'resource.script',
+      },
+    ];
+
+    for (const { initiatorType, op } of table) {
+      const entry: ResourceEntry = {
+        initiatorType,
+      };
+      addResourceSpans(transaction, entry, '/assets/to/me', 123, 234, 465);
+
+      // eslint-disable-next-line @typescript-eslint/unbound-method
+      expect(transaction.startChild).toHaveBeenLastCalledWith(
+        expect.objectContaining({
+          op,
+        }),
+      );
+    }
+  });
+
+  it('allows for enter size of 0', () => {
+    const entry: ResourceEntry = {
+      initiatorType: 'css',
+      transferSize: 0,
+      encodedBodySize: 0,
+      decodedBodySize: 0,
+    };
+
+    addResourceSpans(transaction, entry, '/assets/to/css', 100, 23, 345);
+
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    expect(transaction.startChild).toHaveBeenCalledTimes(1);
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    expect(transaction.startChild).toHaveBeenLastCalledWith(
+      expect.objectContaining({
+        data: {
+          ['Decoded Body Size']: entry.decodedBodySize,
+          ['Encoded Body Size']: entry.encodedBodySize,
+          ['Transfer Size']: entry.transferSize,
+        },
+      }),
+    );
+  });
+});