This app lets you open TikTok video links without the TikTop app.
Installing this doesn't add anything to your app drawer; all it does is register a handler for https://vm.tiktok.com links and https://m.tiktok.com links. The app is roughly equivalent to viewing the link in an incognito-mode Chrome tab, but with the added feature of enforcing the correct aspect ratio on the video (on square-ish devices the TikTok website cuts off the top and bottom of videos).
When you click on a https://vm.tiktok.com link (such as https://vm.tiktok.com/ZMeXFW9yE/ ) in some other app you should get a popup asking if you want to open it with TokViewer or your regular web browser. If you miss this and accidentally set your browser to be the default app the popup will no longer appear, and you will have to go into app settings for TokViewer and assign it as the default manually.
Once you choose TokViewer the video will open full-screen.
This app is not a replacement for the full TikTok app. It is not intended for logging in or posting videos. If you're looking for the full TikTok app go get it here: https://play.google.com/store/apps/details?id=com.zhiliaoapp.musically
This app can also handle https://www.google.com/url links since some popular messaging apps (such as Hangouts) wrap outbound links in one of these before sending out the link. When TokViewer intercepts a https://www.google.com/url intent it strips off the redirect and plays the result (if it's a TikTok video). Otherwise it resubmits the link back to your device (probably resulting in it opening in your web browser). If you don't want this behavior just don't set TokViewer as the default handler for google.com links when prompted.