diff --git a/tools/find-inactive-collaborators.js b/tools/find-inactive-collaborators.js
new file mode 100644
index 00000000000000..c7359fd1a0be33
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+++ b/tools/find-inactive-collaborators.js
@@ -0,0 +1,77 @@
+'use strict';
+
+// 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.
+
+const SINCE = process.argv[2] || '6 months ago';
+
+const childProcess = require('child_process');
+const fs = require('fs');
+const path = require('path');
+
+// Retrieve all commit authors during the time period.
+const authors = childProcess.execSync(
+  `git shortlog -n -s --since="${SINCE}"`,
+  { cwd: path.resolve(__dirname, '..'),
+    encoding: 'utf8',
+    stdio: ['inherit', 'pipe', 'pipe'] }
+).split('\n')
+ .map((line) => line.trim(' ').split('\t')[1])
+ .filter((val) => !!val);
+
+// Retrieve all commit landers during the time period.
+const landers = childProcess.execSync(
+  `git shortlog -n -s -c --since="${SINCE}"`,
+  { cwd: path.resolve(__dirname, '..'),
+    encoding: 'utf8',
+    stdio: ['inherit', 'pipe', 'pipe'] }
+).split('\n')
+ .map((line) => line.trim(' ').split('\t')[1])
+ .filter((val) => !!val);
+
+// Retrieve all approving reviewers of landed commits during the time period.
+const approvingReviewers = childProcess.execSync(
+  `git log --since="${SINCE}" | egrep "^    Reviewed-By: " | sort | uniq `,
+  { cwd: path.resolve(__dirname, '..'),
+    encoding: 'utf8',
+    stdio: ['inherit', 'pipe', 'pipe'] }
+).split('\n')
+ .filter((line) => !!line)
+ .map((line) => /^    Reviewed-By: ([^<]+)/.exec(line)[1].trim());
+
+// Retrieve list of current collaborators from README.md.
+const readmeText = fs.readFileSync(
+  path.resolve(__dirname, '..', 'README.md'),
+  'utf8'
+);
+let processingCollaborators = false;
+const collaborators = readmeText
+  .split('\n')
+  .filter((line) => {
+    const isCollaborator = processingCollaborators && line.length;
+    if (line === '### Collaborators') {
+      processingCollaborators = true;
+    }
+    if (line === '### Collaborator emeriti') {
+      processingCollaborators = false;
+    }
+    return line.startsWith('**') && isCollaborator;
+  })
+  .map((line) => line.split('**')[1].trim());
+
+console.log(`${authors.length.toLocaleString()} authors have made commits since ${SINCE}.`);
+console.log(`${landers.length.toLocaleString()} landers have landed commits since ${SINCE}.`);
+console.log(`${approvingReviewers.length.toLocaleString()} reviewers have approved landed commits since ${SINCE}.`);
+console.log(`${collaborators.length.toLocaleString()} collaborators currently in the project.`);
+
+const inactive = collaborators.filter((collaborator) =>
+  !authors.includes(collaborator) &&
+  !landers.includes(collaborator) &&
+  !approvingReviewers.includes(collaborator)
+);
+
+if (inactive.length) {
+  console.log('\nInactive collaborators:\n');
+  console.log(inactive.join('\n'));
+}