> ## Documentation Index > Fetch the complete documentation index at: https://docs.exode.biz/llms.txt > Use this file to discover all available pages before exploring further. # Mobile app > How to open a specific lesson (or another screen) from your app directly in the ExodeBiz app via a deep link, with optional token-based sign-in From your native app, you can open the ExodeBiz app directly on the screen you need — select the school, sign the user in with a token if needed, and open a lesson. All it takes is opening the scheme link the standard way (`Intent.ACTION_VIEW` on Android / `UIApplication.open` on iOS). ## Link format The deep link uses the app's URL scheme `exodebizapp://`. All parameters go into a single `data` parameter — a URL-encoded query string: ``` exodebizapp://?data= ``` Parameters inside `data`: Always `open-page`. The school's domain (FQDN), for example `my-school.com` or `my-school.exode.biz`. Screen identifier. For a lesson, see the "Open a lesson" section. JSON with the screen parameters, for example `{"page":"1","courseId":"42","lessonId":"123"}`. A list of additional actions (for example, sign-in). See the "extra" section. Parameter values contain special characters and require double encoding: first build the query string `action=...&domain=...` (with URL-encoded values), then encode it as a whole and put it into `data`. Don't build it manually — use standard builders (`URLSearchParams`, `Uri.Builder`, `URLComponents`), see the code examples below. ## Open a lesson | Field | Value | | - | - | | `pageId` | `/courses/:page([0-9]+)/:courseId([0-9]+)/study/:lessonId([0-9]+)` | | `params` | `{"page":"1","courseId":"","lessonId":""}` | * `page` — the page in the course list; to go to a lesson, specify `"1"`. * `courseId`, `lessonId` — the course and lesson IDs in your school. A ready-made link — substitute `DOMAIN`, `COURSE_ID`, `LESSON_ID`: ``` exodebizapp://?data=action%3Dopen-page%26domain%3DDOMAIN%26pageId%3D%252Fcourses%252F%253Apage%2528%255B0-9%255D%252B%2529%252F%253AcourseId%2528%255B0-9%255D%252B%2529%252Fstudy%252F%253AlessonId%2528%255B0-9%255D%252B%2529%26params%3D%257B%2522page%2522%253A%25221%2522%252C%2522courseId%2522%253A%2522COURSE_ID%2522%252C%2522lessonId%2522%253A%2522LESSON_ID%2522%257D ``` ### Other screens By changing `pageId` and `params`, you can open any screen: | Screen | `pageId` | `params` | | - | - | - | | Lesson | `/courses/:page([0-9]+)/:courseId([0-9]+)/study/:lessonId([0-9]+)` | `{"page":"1","courseId":"42","lessonId":"123"}` | | Course | `/course/:courseId([0-9_A-Za-z]+)` | `{"courseId":"42"}` | Need another screen? Contact support and we'll tell you the correct `pageId` and parameters. ## extra — nested actions (sign-in) The `extra` parameter lets you pass a list of actions to the app that run along with opening it — for example, token-based sign-in. `extra` is `base64url(JSON.stringify({ actions: [...] }))`. JSON structure: ```json theme={null} { "actions": [ { "type": "login-by-token", "token": "USER_TOKEN" } ] } ``` Supported actions: | `type` | Fields | Description | | - | - | - | | `login-by-token` | `token` | Sign the user in with a token | | `open-page` | `pageId`, `params` | Navigate to a screen | The execution order is guaranteed: first the actions from `extra` (in array order), then the navigation from `open-page`. So an `open-page` link + `extra:[{login-by-token}]` does exactly this: open the app → sign in → open the page. The token is created with the [Create a session token](/en/exode-api/school/user/session/auth-token) method (`POST /saas/v2/user/session/auth-token`). Take the value of the `token` field from the response. `extra = base64url(JSON.stringify({ actions: [{ type: 'login-by-token', token }] }))`. Example (with the placeholder token `USER_TOKEN`): ``` eyJhY3Rpb25zIjpbeyJ0eXBlIjoibG9naW4tYnktdG9rZW4iLCJ0b2tlbiI6IlVTRVJfVE9LRU4ifV19 ``` Add `extra` to the query string inside `data` — the app switches the school, signs the user in and opens the lesson. A link with `login-by-token` signs in as a specific user — anyone who has the link will be signed in as that user. Such links must be short-lived / personal and must not be published. Use base64url specifically (`-`/`_` instead of `+`/`/`, no `=` padding) — regular base64 may not pass through a query string correctly. ## Building and opening the link in code ```js JavaScript theme={null} const SCHEME = 'exodebizapp'; const LESSON = '/courses/:page([0-9]+)/:courseId([0-9]+)/study/:lessonId([0-9]+)'; const b64url = (obj) => btoa(String.fromCharCode(...new TextEncoder().encode(JSON.stringify(obj)))) .replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, ''); function buildLessonLink({ domain, courseId, lessonId, page = 1, token }) { const inner = new URLSearchParams({ action: 'open-page', domain, pageId: LESSON, params: JSON.stringify({ page: String(page), courseId: String(courseId), lessonId: String(lessonId), }), }); // optional: auto sign-in if (token) { inner.set('extra', b64url({ actions: [{ type: 'login-by-token', token }] })); } return `${SCHEME}://?data=${encodeURIComponent(inner.toString())}`; } ``` ```kotlin Android theme={null} fun buildLessonLink(domain: String, courseId: Long, lessonId: Long, page: Int = 1): String { val pageId = "/courses/:page([0-9]+)/:courseId([0-9]+)/study/:lessonId([0-9]+)" val paramsJson = """{"page":"$page","courseId":"$courseId","lessonId":"$lessonId"}""" val inner = Uri.Builder() .appendQueryParameter("action", "open-page") .appendQueryParameter("domain", domain) .appendQueryParameter("pageId", pageId) .appendQueryParameter("params", paramsJson) .build().encodedQuery ?: "" return "exodebizapp://?data=" + Uri.encode(inner) } // open with a fallback try { startActivity(Intent(Intent.ACTION_VIEW, Uri.parse(link))) } catch (e: ActivityNotFoundException) { // app not installed → open the store / website } ``` ```swift iOS theme={null} func buildLessonLink(domain: String, courseId: Int, lessonId: Int, page: Int = 1) -> URL { let pageId = "/courses/:page([0-9]+)/:courseId([0-9]+)/study/:lessonId([0-9]+)" let paramsJson = "{\"page\":\"\(page)\",\"courseId\":\"\(courseId)\",\"lessonId\":\"\(lessonId)\"}" var inner = URLComponents() inner.queryItems = [ .init(name: "action", value: "open-page"), .init(name: "domain", value: domain), .init(name: "pageId", value: pageId), .init(name: "params", value: paramsJson), ] let data = (inner.percentEncodedQuery ?? "") .addingPercentEncoding(withAllowedCharacters: .alphanumerics) ?? "" return URL(string: "exodebizapp://?data=\(data)")! } // open with a fallback UIApplication.shared.open(link, options: [:]) { success in if !success { /* app not installed → open the store / website */ } } ``` ## Behavior * The deep link works only if the app is installed. If it isn't, the OS opens nothing: handle this yourself and show a fallback (the app store or the school's website). On Android, catch `ActivityNotFoundException`; on iOS, check `success == false` in the `open` completion handler. * If the school hasn't been added to the app yet, it is added automatically and becomes active. * Navigation follows the usual authorization rules: without an `extra` sign-in, an unauthenticated user sees the sign-in screen. ## Troubleshooting | Symptom | Cause / solution | | - | - | | Nothing happens when opening the link | The app is not installed, or the context doesn't recognize custom schemes. Implement a fallback. | | The wrong lesson opened | Check `pageId` (character for character) and the values in `params`; make sure `data` is built correctly (double encoding). | | "School not found" | Incorrect `domain`. Specify the school's exact FQDN. | | The sign-in screen opens | The user is not signed in / has no access. For auto sign-in, use `extra` with `login-by-token`. | *** *Updated: 2026-09-25 14:33 UTC* This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.