Latch Install

Escape does nothing.

Latch pins a lecture or a PDF in full screen. When it gets hard and your hand goes for the way out, nothing happens. Built for the version of you who wants to quit.

Install it, free View on GitHub

Go on, press Esc on this page.

You are forty minutes into a lecture.

It gets hard. Your hand reaches for ⌘ T before you have decided anything.

Latch is what happens next.

What it stops

Once the lecture is in full screen and Latch is on, the usual ways out stop working.

  • EscNothing
  • ⌘R ⌘LNothing
  • ⌘T ⌘W ⌘N ⌘1 to 9Nothing
  • F or the player's full screen buttonNothing
  • Switching to another tabYou are put back
  • Typing a different addressYou are put back
  • Closing the tabIt reopens, still locked
  • Holding Esc for two secondsThe lock screen

The video pauses as well, so a lecture is never playing to an empty room. Escape is held back with the browser's Keyboard Lock API, the one cloud gaming sites use. Holding it for two seconds always forces full screen off; no page can take that away, and none should.

Getting out takes a hold

A click is a reflex. Eight seconds is a decision. Letting go starts the count again, so it can't be chipped away in bursts, and the popup and the shortcut can't end a lock early.

The Latch lock screen: You already decided this. A ring shows 58% of the lecture done, with Back to the lecture and Hold to unlock buttons.
You are 34 minutes in. The expensive part is already paid. Starting is what costs you, and you did that 34 minutes ago.
17 days. This is the one that breaks it. Streaks do not end on the hard days. They end on an ordinary Tuesday when someone decides one skip does not count.

Try it. In Latch it is eight seconds; here, three.

48 platforms, and your PDFs

The lock is a browser feature, not a YouTube one, so it works wherever the lecture is.

Video and the big courses

YouTube, Udemy, Coursera, edX, Udacity, FutureLearn, Codecademy, Pluralsight, Skillshare, DataCamp, Educative, Alison, MasterClass, Domestika, LinkedIn Learning, O'Reilly

India

NPTEL, SWAYAM, Unacademy, Physics Wallah, Vedantu, BYJU'S, Doubtnut, Testbook, Scaler, Coding Ninjas, upGrad, Great Learning, Simplilearn

Developer courses

Frontend Masters, egghead.io, Laracasts, Scrimba, Treehouse, Vue School, LeetCode, Code with Mosh

Universities

MIT OpenCourseWare, Stanford Online, Khan Academy, Brilliant

Course hosts

Teachable, Thinkific, Kajabi, Podia, Maven, Vimeo

Readings

Google Drive's file viewer, and any PDF open in Chrome, including ones on your own disk. Press the Lock this reading button Latch adds to the corner.

And anywhere else. An unlisted site still locks: Latch finds the full screen button by its accessibility label, which players rarely change, instead of class names, which they change all the time.

Every way out, written down

Using Latch turned up eight real ways around it. Patching them one at a time kept missing the pattern behind each, so all of them are documented, with what closes them.

  • Guards that only ran in full screenWhich is false exactly when the lock screen is up, so the screen shown to someone trying to leave was the least protected part.
  • Load orderAfter a reload the lock screen goes up before the site has built its player, so some things need doing twice.
  • RacesClosing the locked tab reopens it, and two guards read the briefly missing tab as the end of the session. Now exactly one place can end one.

Left open on purpose: holding Escape, removing the extension, quitting Chrome, ⌘Tab, incognito, other extensions, another browser. A lock with no way out would be a dangerous thing to build. The full audit is in ESCAPES.md.

Install it in two minutes

Latch is not on the Chrome Web Store yet, so you load it yourself. It works in Chrome and other Chromium browsers.

  1. Get the code

    In Terminal:

    git clone https://github.com/saksham10arora-dotcom/latch.git

    No git? Download the zip and unzip it somewhere it can stay.

  2. Load it in Chrome

    Open chrome://extensions, turn on Developer mode, click Load unpacked, and choose the latch folder.

  3. Close the back doors

    On Latch's Details page, turn on Allow in Incognito, or a private window is an easy way out. If you read PDFs from your own disk, turn on Allow access to file URLs too.

  4. Lock a lecture

    Play a lecture, go full screen, and press Option Shift L. For a PDF, press the Lock this reading button in the corner. If the shortcut does nothing, another extension took it; set your own at chrome://extensions/shortcuts.

Privacy

Latch collects nothing, sends nothing, and has no server. There is no network code in it at all.

Six values, kept on your computer, readable only by Latch. Uninstalling removes them.

  • armedwhether the lock is on
  • engagedwhether full screen started under this lock
  • holdSecondshow long the unlock hold lasts
  • phrasethe optional phrase you retype to unlock
  • strictwhether to warn before closing the tab
  • breakshow many times the lock screen has appeared

From the page, it reads only the video's time and the lecture's title, to draw the lock screen. The full policy.

Questions

Is it free?

Yes, and open source under the MIT license.

Can I get trapped?

No. Holding Escape for two seconds always leaves full screen and brings up the lock screen, and from there an eight-second hold unlocks it. You can also remove the extension or quit Chrome. Latch makes leaving cost something; it does not make it impossible.

Which browsers?

Chrome and other Chromium browsers, on Mac, Windows and Linux. Firefox would need its own version.

My course site isn't on the list.

Try it anyway. The lock works on unlisted sites by finding the player's full screen button through its accessibility label. If something doesn't work, open an issue on GitHub.

Does it work on every PDF on the web?

No. It locks PDFs on the platforms above and files on your own disk. Covering every PDF online would mean asking to read every website, which is far more access than a focus tool should have.

Why can't the popup or the shortcut end a lock?

Every way out has to cost the same, or the cheapest one becomes the only one anybody uses.