Projects / EchoLoc

Mobile

EchoLoc

A privacy-first live location sharing app. Users share location with a group only for a defined time window, not as always-on tracking. The app includes group chat, invites, and a live map over Socket.IO, backed by a custom API.

ExpoReact NativeSocket.IONode.jsAuth
GitHubAppAPI

01 Walkthrough

One short demo and two screens from the product.

Screenshot 01
Screenshot 02

02 Stack layers

Mobile

ExpoReact NativeMapsChat

Realtime

Socket.IOTimed sessions

Backend

Echo_APIAuthGroups

03 Architecture

REQUESTWS session.start(group, ttl)tracing
authpingsverifyexpirybroadcastExpo AppReact NativeCLIENTREST APIAuth · groupsSVCSocket.IOPings · fanoutSVCOAuthGoogle · AppleEXTSession ManagerTTL · expirySVCMongoDBGroups · pingsDATA

Expo authenticates over REST, then streams location pings over Socket.IO. Session manager enforces TTL and ends sharing when time is up.

  • Full Expo/React Native app with timed sharing sessions
  • Group creation, invites, and in-group chat
  • Live map + Socket.IO; email and Google/Apple sign-in

04 Engineering challenges

01

Timed privacy model

Sharing is scoped to a user-defined window. Sessions expire on the server, so a client bug cannot leave tracking on.

02

Live group map

Location pings fan out over Socket.IO rooms to group members in real time while a session is active.

03

Event-based groups

Invite codes, membership roles, and in-group chat support temporary sharing circles around real events.

04

Multi-provider auth

Email plus Google and Apple sign-in for low-friction mobile onboarding.

05 Trade-offs & decisions

Socket.IOvsPolling

Sub-second location updates with connection fallbacks that survive flaky mobile networks.

ExpovsBare React Native

Managed workflow shipped both platforms fast; native modules were not a blocker.

TTL sessionsvsAlways-on sharing

Privacy is the product. Expiry is enforced in the data model, not only in the UI.

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