Why Feishu can't just work out of the box like Apple Calendar
The way Feishu's "custom app" mechanism works means an app can only be used by the company that created it — there's no way for SnapCal to build one official app that covers every Feishu tenant in the world. So the Feishu path works on a BYO (bring your own app) model: you create an app that belongs to your own company on the Feishu Open Platform, enter its App ID and App Secret into SnapCal, and from then on every event SnapCal reads from a screenshot can sync into your company's Feishu Calendar.
Five steps to set it up
Step 1: Create a custom app
Open the developer console on the Feishu Open Platform and create a "custom app." A name and an icon are all you need — there's no need to fill in much else.
Step 2: Enable calendar permissions
Go to the app's "Permissions" page, search for calendar:calendar (calendar read/write), and enable it.
Step 3: Add the redirect URL
Find the redirect URL setting under "Security Settings" and add the redirect URL SnapCal provides to the whitelist. This step is required by the OAuth authorization flow — get the address wrong or skip it, and authorization will fail outright later on.
Step 4: Create and release an app version (the step people miss most)
Under "Version Management & Release," create a version, set the availability scope to "all members" (or at least include yourself), and submit it for release. A custom app has no released version by default — only its creator can see it. If you're not your team's Feishu admin, it's easy to get stuck here not knowing who to ask for approval. The good news: the creator of a custom app is usually the admin for that app too, so you can approve it yourself. Skip this step, and none of your coworkers will be able to authorize through this app.
Step 5: Copy the App ID and App Secret
On the app's "Credentials & Basic Info" page, copy the App ID and App Secret, paste them into SnapCal's Feishu settings page, and tap Connect. Feishu will pop up an authorization page — approve it, and you're connected.
Already set up by a coworker? Just ask them for the credentials
If the released version was set to "all members," only one person at the company needs to complete the first four steps in full. Every coworker after that doesn't need to create a new app — just ask that person for the App ID and App Secret, enter them into the two fields in SnapCal's quick-connect flow, and you're connected, without ever touching the Feishu Open Platform yourself.
Is the App Secret safe?
The App Secret is stored in your phone's Keychain. The process of exchanging it for an authorization token is relayed through SnapCal's server — this is a requirement Feishu enforces (a Secret isn't allowed to be exchanged for a token directly on the client side). This Secret belongs only to your own company's Feishu app, and it never crosses paths with other companies' or other users' data.
