Does LeetCode Track Tab Switching or Copy-Paste?

LeetCode documents no tab-switch tracking and no copy-paste detection on any surface. As of September 9, 2026, the closest thing in LeetCode's own materials is the contest Code Replay, which since May 2026 "includes editor activity status information," and a contest rule that prohibits moving problem text or code into any external tool. Whether a paste is detected is therefore the wrong question on LeetCode. The rule bans the act; the replay shows the result.

What a browser can see, and what LeetCode says it uses

Any web page can learn when its tab loses focus or visibility. That is standard browser behavior, covered in how interview websites detect tab switching. Platforms that use it say so: HackerRank documents "Out of Window Duration" in its reports, for example.

LeetCode's documentation does not. Its feature release notes, updated June 5, 2026, describe the editor, the judge, contests, and Ask Leet in detail and never mention focus, visibility, or window events. Its privacy policy lists IP address and session cookies and states that "no other personal information is collected." LeetCode could add focus tracking without changing either page, so read this as undocumented rather than impossible.

What Code Replay records

Code Replay is the one behavioral record LeetCode publishes. The release notes introduced it in May 2025: "Now you can replay your contest performance from the Contest Ranking." In May 2026 the notes added: "Editor Activity Status: Code Replay now includes editor activity status information for greater visibility into the contest experience."

LeetCode does not define "editor activity status" further. Read literally, it reports whether the editor was active over time, which would make an idle gap followed by a large block of code visible to anyone reviewing the replay. That is an inference from the feature name, not a documented tab tracker. What the replay shows for certain is the sequence in which code appeared in the editor, which is enough to distinguish incremental typing from a single paste.

What the contest rule says about pasting

The contest rules, updated September 26, 2024, do not mention the clipboard. They prohibit the direction of travel: "The use of code generation tools or any external assistance for solving problems is strictly prohibited. This includes, but is not limited to, actions such as inputting problem statements, test cases, or solution code into external assistance tools."

Pasting a prepared template of your own into the editor is not addressed by the rules, and contestants have asked about it in the comments without an official answer. What is addressed is anything that flows outward to a tool that helps solve the problem. Enforcement then runs on similarity, as described in how LeetCode detects contest cheating: identical or near-identical code across accounts is what the checker finds, regardless of how it entered the editor.

Outside contests, nothing is tracked or prohibited

On practice problems, LeetCode ships its own assistant. The release notes describe Ask Leet with "Smart Suggestions: Brainstorm solutions, optimize code, generate test cases, and debug," and a "Quick Fix" that can "analyze and fix code errors directly from the editor." There is no rule against tab switching, pasting, or AI on practice problems because the platform provides AI in the editor.

Mock Assessments are practice too. LeetCode Interview is a live session where the interviewer watches the shared editor in real time, so a paste is visible to a person rather than logged by a system.

The test that does track tabs is probably not on LeetCode

If your online assessment displayed a warning when you switched tabs, blocked paste, or asked for full-screen mode, it was not running on leetcode.com. Those are HackerRank, CodeSignal, and Codility behaviors, documented by each vendor. What a LeetCode online assessment actually is shows how to identify the real platform from the invitation, and the HackerRank proctoring inventory lists the events that platform logs by default.

What this means for candidates

In a LeetCode contest, assume the finished code and its typing history are public and comparable, and treat the external-assistance rule as absolute; the rule, not a tab counter, is what gets enforced. In practice mode, switch tabs and paste freely; LeetCode built an assistant into the page. In any employer assessment, check the domain first and read that platform's rules, because the tab tracking you have heard about is theirs.

The complete list of what each LeetCode surface records is in what LeetCode records across contests, Interview, and mock tests.