diff --git a/tools/find-inactive-collaborators.mjs b/tools/find-inactive-collaborators.mjs
new file mode 100755
index 00000000000000..578adf05fb78c7
--- /dev/null
+++ b/tools/find-inactive-collaborators.mjs
@@ -0,0 +1,95 @@
+#!/usr/bin/env node
+
+// Identify inactive collaborators. "Inactive" is not quite right, as the things
+// this checks for are not the entirety of collaborator activities. Still, it is
+// a pretty good proxy. Feel free to suggest or implement further metrics.
+
+import cp from 'node:child_process';
+import fs from 'node:fs';
+import readline from 'node:readline';
+
+const SINCE = process.argv[2] || '6 months ago';
+
+async function runGitCommand(cmd, mapFn) {
+  const childProcess = cp.spawn('/bin/sh', ['-c', cmd], {
+    cwd: new URL('..', import.meta.url),
+    encoding: 'utf8',
+    stdio: ['inherit', 'pipe', 'inherit'],
+  });
+  const lines = readline.createInterface({
+    input: childProcess.stdout,
+  });
+  const errorHandler = new Promise(
+    (_, reject) => childProcess.on('error', reject)
+  );
+  const returnedSet = new Set();
+  await Promise.race([errorHandler, Promise.resolve()]);
+  for await (const line of lines) {
+    await Promise.race([errorHandler, Promise.resolve()]);
+    const val = mapFn(line);
+    if (val) {
+      returnedSet.add(val);
+    }
+  }
+  return Promise.race([errorHandler, Promise.resolve(returnedSet)]);
+}
+
+// Get all commit authors during the time period.
+const authors = await runGitCommand(
+  `git shortlog -n -s --since="${SINCE}"`,
+  (line) => line.trim().split('\t', 2)[1]
+);
+
+// Get all commit landers during the time period.
+const landers = await runGitCommand(
+  `git shortlog -n -s -c --since="${SINCE}"`,
+  (line) => line.trim().split('\t', 2)[1]
+);
+
+// Get all approving reviewers of landed commits during the time period.
+const approvingReviewers = await runGitCommand(
+  `git log --since="${SINCE}" | egrep "^    Reviewed-By: "`,
+  (line) => /^    Reviewed-By: ([^<]+)/.exec(line)[1].trim()
+);
+
+async function retrieveCollaboratorsFromReadme() {
+  const readmeText = readline.createInterface({
+    input: fs.createReadStream(new URL('../README.md', import.meta.url)),
+    crlfDelay: Infinity,
+  });
+  const returnedArray = [];
+  let processingCollaborators = false;
+  for await (const line of readmeText) {
+    const isCollaborator = processingCollaborators && line.length;
+    if (line === '### Collaborators') {
+      processingCollaborators = true;
+    }
+    if (line === '### Collaborator emeriti') {
+      processingCollaborators = false;
+      break;
+    }
+    if (line.startsWith('**') && isCollaborator) {
+      returnedArray.push(line.split('**', 2)[1].trim());
+    }
+  }
+  return returnedArray;
+}
+
+// Get list of current collaborators from README.md.
+const collaborators = await retrieveCollaboratorsFromReadme();
+
+console.log(`${authors.size.toLocaleString()} authors have made commits since ${SINCE}.`);
+console.log(`${landers.size.toLocaleString()} landers have landed commits since ${SINCE}.`);
+console.log(`${approvingReviewers.size.toLocaleString()} reviewers have approved landed commits since ${SINCE}.`);
+console.log(`${collaborators.length.toLocaleString()} collaborators currently in the project.`);
+
+const inactive = collaborators.filter((collaborator) =>
+  !authors.has(collaborator) &&
+  !landers.has(collaborator) &&
+  !approvingReviewers.has(collaborator)
+);
+
+if (inactive.length) {
+  console.log('\nInactive collaborators:');
+  console.log(inactive.join('\n'));
+}