memory-leak-debugging

chromedevtools/chrome-devtools-mcp

Diagnose and fix memory leaks in JavaScript/Node.js apps using Chrome DevTools MCP heap snapshot tools.

What is memory-leak-debugging?

This skill provides workflows for finding, diagnosing, and fixing memory leaks in JavaScript and Node.js applications. Use it when investigating high memory usage, OOM errors, or when you need to capture and compare heap snapshots to identify what's consuming memory.

Capture heap snapshots at baseline, target, and final states to isolate memory growth
Compare snapshots to identify which object classes or types are growing unexpectedly
Inspect retaining chains and dominator trees to understand why objects remain in memory
Filter for common leak causes: detached DOM nodes, unremoved event listeners, closures, console references, and unbounded caches
Analyze duplicate strings and object metadata to pinpoint the source of memory retention

How to install memory-leak-debugging

npx skills add https://github.com/chromedevtools/chrome-devtools-mcp --skill memory-leak-debugging

Prerequisites

Chrome DevTools MCP server must be started with the `--memoryDebugging` flag to access advanced heap snapshot tools
For browser debugging: access to the target web application via Chrome DevTools MCP page tools
For Node.js debugging: ability to trigger heap snapshots on the running process

Claude Code

Cursor

Windsurf

Cline

How to use memory-leak-debugging

1.Verify that the MCP server has `--memoryDebugging` enabled; check the MCP configuration if advanced memory tools are unavailable
2.Capture a baseline heap snapshot in the initial application state using `take_heapsnapshot`
3.Perform the suspected memory-leaking operation (e.g., repeat user interactions 10 times, or trigger a specific code path)
4.Capture a target heap snapshot after the operation to compare against baseline
5.Revert the application to its original state and capture a final snapshot to confirm if memory is released
6.Use `get_heapsnapshot_summary` on each snapshot to confirm they load and compare high-level memory totals
7.Use `compare_heapsnapshots` on baseline and target snapshots to identify which object classes grew unexpectedly
8.For suspicious classes, use `get_heapsnapshot_class_nodes` to list instances, then `get_heapsnapshot_retainers` or `get_heapsnapshot_retaining_paths` to understand why they are retained

Use cases

Good for

Investigate a production Node.js service reporting OOM errors by capturing snapshots before and after a suspected operation
Debug a browser application where repeated user interactions cause memory to grow; capture snapshots to compare baseline vs. after 10 iterations
Identify why a specific object class (e.g., Event, Listener, Cache) is retaining thousands of instances by inspecting its retaining paths
Find detached DOM nodes or unremoved event listeners keeping large object graphs alive in a frontend app
Analyze string duplication in heap snapshots when string memory dominates the overall leak

Who it's for

Backend engineers debugging Node.js memory issues and OOM crashes
Frontend developers investigating browser memory leaks and performance degradation
DevOps and SRE teams analyzing production memory consumption patterns
QA engineers reproducing and validating memory leak fixes

memory-leak-debugging FAQ

Why shouldn't I read raw .heapsnapshot files directly?

Raw .heapsnapshot files are extremely large and will consume too many tokens. Always use Chrome DevTools MCP heap snapshot tools (get_heapsnapshot_summary, compare_heapsnapshots, etc.) to summarize and inspect snapshots efficiently.

What are the most common causes of memory leaks in JavaScript?

Common culprits include detached DOM nodes, unhandled closures, global variables, event listeners not being removed, unbounded caches, and objects retained by console logging. The skill provides filters to identify each category.

How do I know if a memory leak is in the browser or Node.js?

Use the skill's isolation workflow: capture snapshots in the suspected environment (browser via page tools, or Node.js process), compare them, and inspect retaining paths to pinpoint where objects are being held.

Should I always null out detached DOM nodes when I find them?

No. Detached DOM nodes are sometimes intentional caches. Always inspect the retaining path and ask the user before modifying code to remove them.

What should I do after completing a memory leak investigation?

Use `close_heapsnapshot` for each loaded snapshot to release memory held by the MCP server and avoid accumulating large snapshots in memory.

Full instructions (SKILL.md)

Source of truth, from chromedevtools/chrome-devtools-mcp.

name: memory-leak-debugging description: Diagnoses and resolves memory leaks in JavaScript/Node.js applications. Use when a user reports high memory usage, OOM errors, or wants to capture, compare, or inspect heap snapshots with Chrome DevTools MCP memory tools.

Memory Leak Debugging

This skill provides expert guidance and workflows for finding, diagnosing, and fixing memory leaks in JavaScript and Node.js applications using Chrome DevTools MCP tools.

Prerequisites

Advanced memory debugging tools (compare_heapsnapshots, get_heapsnapshot_details, etc.) are only available when the server is started with the --memoryDebugging flag. First check if these tools are available; if not, try to read the MCP configuration file to check if --memoryDebugging is enabled.

Core Principles

Prefer MCP memory tools: Do NOT attempt to read raw .heapsnapshot files directly, as they are extremely large and will consume too many tokens. Use the Chrome DevTools MCP heap snapshot tools to summarize, compare, and inspect snapshots.
Isolate the Leak: Determine if the leak is in the browser (client-side) or Node.js (server-side).
Common Culprits: Look for detached DOM nodes, unhandled closures, global variables, event listeners not being removed, and caches growing unbounded. Note: Detached DOM nodes are sometimes intentional caches; always ask the user before nulling them.
Close Loaded Snapshots: Heap snapshots can be large. After completing an investigation, use close_heapsnapshot for each loaded snapshot to release memory held by the MCP server.

Workflows

1. Capturing Snapshots

When investigating a frontend web application memory leak, utilize the chrome-devtools-mcp tools to interact with the application and take snapshots.

Use page-scoped tools like click, navigate_page, fill, etc. (specifying pageId) to manipulate the page into the desired state.
Revert the page back to the original state after interactions to see if memory is released.
Repeat the same user interactions 10 times to amplify the leak.
Use take_heapsnapshot (with pageId) to save .heapsnapshot files to disk at baseline, target (after actions), and final (after reverting actions) states.

2. Comparing Snapshots

Once you have generated .heapsnapshot files using take_heapsnapshot, compare them with Chrome DevTools MCP memory tools.

Start with get_heapsnapshot_summary for each snapshot to confirm that the files load and to compare high-level totals.
Use compare_heapsnapshots to compare baseline and target snapshots. Start without classIndex for the summary diff, then request detailed class diffs only for suspicious growth by specifying classIndex.
Use the summary output from compare_heapsnapshots before drilling into specific node IDs.

3. Inspecting Retainers and Dominator Chains

When a class or object type grows unexpectedly, inspect the retaining chain and dominators with the MCP tools before changing code.

Use get_heapsnapshot_class_nodes to list instances of the suspicious class.
Use get_heapsnapshot_retainers, get_heapsnapshot_retaining_paths, get_heapsnapshot_dominators, and get_heapsnapshot_edges to understand why representative nodes are still reachable.
Use get_heapsnapshot_object_details with a specific nodeId to retrieve detailed object metadata (size, type, distance, and DOM detachedness).
Use get_heapsnapshot_duplicate_strings when string growth dominates the diff.
Read references/common-leaks.md for examples of common memory leaks and how to fix them after the retaining path points at application code.

4. Advanced Analysis and Categorized Filters

Use built-in MCP memory tools and filters to pinpoint specific leak categories directly without external tools.

Use get_heapsnapshot_details or get_heapsnapshot_class_nodes with filterName to target common leak causes:
- objectsRetainedByDetachedDomNodes: Identifies detached DOM elements retained in memory.
- objectsRetainedByEventHandlers: Identifies objects kept alive by unremoved event listeners.
- objectsRetainedByContexts: Identifies objects trapped in closures or execution contexts.
- objectsRetainedByConsole: Identifies objects retained by console logging.