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Fetch Latest Version of App — Smart Update Links

· 6 min read
Serhii Kuianov
Serhii Kuianov
DevOps

Ever needed a download link that always points to the latest version of your app — one you can put on a landing page, in a README, or inside a CI pipeline and never touch again? That's exactly what faynoSync's /apps/latest endpoint is for.

Instead of hardcoding myapp-1.2.3.dmg and updating it on every release, you point users at a stable URL and faynoSync resolves it to the newest matching build. This post walks through the endpoint with copy-paste examples for landing pages, OS auto-detection, shell scripts, and Docker.

Looking to check for updates from inside a running app (Electron, Tauri, Squirrel)? That's a different endpoint — /checkVersion. See How to Setup Auto Update for Electron App. /apps/latest is for download links; /checkVersion is for in-app update checks.

Meet Our Example App 🎮​

Let's imagine we have an app called "SpaceExplorer" with the following setup:

Channels:​

  • 🚀 stable - Production releases
  • 🧪 beta - Testing versions
  • 🌙 nightly - Daily builds

Platforms & Architectures:​

  • 💻 Linux (amd64, arm64)
  • 🍎 macOS (amd64, arm64)
  • 🪟 Windows (amd64)

Package Types:​

  • 📦 .deb / .rpm (Linux)
  • 📦 .dmg (macOS)
  • 📦 .exe (Windows)

Endpoint reference​

GET /apps/latest?app_name=<app_name>&channel=stable&platform=linux&arch=amd64&owner=admin
ParameterRequiredDescription
app_name✅The name of the app to fetch
channel✅*Release channel (stable, beta, nightly)
platform❌Platform (linux, darwin, windows)
arch❌Architecture (amd64, arm64)
package❌Package type (deb, rpm, dmg, exe)
owner✅Your admin user name

* channel becomes mandatory once you've defined channels for the app. If your app has no channels configured, you can omit it.

Two behaviors make this endpoint convenient:

  • Dynamic responses — the more parameters you supply, the narrower the result. Supply only app_name + channel and you get every build in that channel; add platform/arch/package to drill down.
  • Automatic redirection — when your filters resolve to a single build, faynoSync responds with an HTTP redirect straight to the download URL. Perfect for "Download" buttons.

Let's Fetch Some Versions! 🎯​

Example 1: Everything in a channel​

curl --location 'http://localhost:9000/apps/latest?app_name=SpaceExplorer&channel=stable&owner=admin'

Returns all builds in the stable channel, grouped by platform → arch → package:

{
  "stable": {
    "linux": {
      "amd64": {
        "deb": { "url": "https://<bucket>.s3.amazonaws.com/SpaceExplorer/stable/linux/amd64/SpaceExplorer-1.2.3.deb" },
        "rpm": { "url": "https://<bucket>.s3.amazonaws.com/SpaceExplorer/stable/linux/amd64/SpaceExplorer-1.2.3.rpm" }
      },
      "arm64": {
        "deb": { "url": "..." },
        "rpm": { "url": "..." }
      }
    },
    "darwin": {
      "amd64": { "dmg": { "url": "..." } },
      "arm64": { "dmg": { "url": "..." } }
    },
    "windows": {
      "amd64": { "exe": { "url": "..." } }
    }
  }
}

Example 2: Platform-Specific​

curl --location 'http://localhost:9000/apps/latest?app_name=SpaceExplorer&channel=stable&platform=linux&owner=admin'

Only Linux builds:

{
  "stable": {
    "linux": {
      "amd64": {
        "deb": { "url": "..." },
        "rpm": { "url": "..." }
      },
      "arm64": {
        "deb": { "url": "..." },
        "rpm": { "url": "..." }
      }
    }
  }
}

Example 3: Exact match (auto-redirect to download)​

curl -L --location 'http://localhost:9000/apps/latest?app_name=SpaceExplorer&channel=stable&platform=linux&arch=amd64&package=deb&owner=admin'

Because this resolves to a single build, faynoSync redirects straight to:

https://<bucket>.s3.amazonaws.com/SpaceExplorer/stable/linux/amd64/SpaceExplorer-1.2.3.deb

The -L flag tells curl to follow the redirect and download the file.

Smart Features 🧠​

  1. Automatic Redirection 🔄

    • If only one build matches your filters, you get an HTTP redirect straight to the download.
    • Ideal for landing pages and direct-download links.

  2. Flexible Responses 🎯

    • Get all builds in a channel, or filter by platform, architecture, and package type.

  3. Stable URLs, moving targets 🎯

    • The link never changes; the file it resolves to advances with every release.

Real-World Use Cases 🌍​

1. Landing page download buttons​

<!-- For Linux users -->
<a href="https://updates.yourdomain.com/apps/latest?app_name=SpaceExplorer&channel=stable&platform=linux&arch=amd64&package=deb&owner=admin">
  Download for Linux (.deb)
</a>

<!-- For macOS users -->
<a href="https://updates.yourdomain.com/apps/latest?app_name=SpaceExplorer&channel=stable&platform=darwin&arch=arm64&package=dmg&owner=admin">
  Download for macOS (.dmg)
</a>

2. One "Download" button that auto-detects the OS​

Detect the visitor's platform in the browser and build the right link on the fly:

<a id="download" href="#">Download SpaceExplorer</a>

<script>
  const base = 'https://updates.yourdomain.com/apps/latest';
  const ua = navigator.userAgent;
  let platform = 'linux', arch = 'amd64', pkg = 'deb';

  if (ua.includes('Mac')) { platform = 'darwin'; arch = 'arm64'; pkg = 'dmg'; }
  else if (ua.includes('Win')) { platform = 'windows'; arch = 'amd64'; pkg = 'exe'; }

  const params = new URLSearchParams({
    app_name: 'SpaceExplorer', channel: 'stable', platform, arch, package: pkg, owner: 'admin',
  });
  document.getElementById('download').href = `${base}?${params}`;
</script>

3. Install the latest build in a shell script​

#!/usr/bin/env bash
set -euo pipefail

URL="https://updates.yourdomain.com/apps/latest?app_name=SpaceExplorer&channel=stable&platform=linux&arch=amd64&package=deb&owner=admin"

curl -L "$URL" -o spaceexplorer.deb
sudo dpkg -i spaceexplorer.deb

4. Always pull the newest build in CI / Docker​

FROM ubuntu:24.04
ARG FAYNOSYNC=https://updates.yourdomain.com/apps/latest?app_name=SpaceExplorer&channel=stable&platform=linux&arch=amd64&package=deb&owner=admin
RUN apt-get update && apt-get install -y curl \
  && curl -L "$FAYNOSYNC" -o /tmp/app.deb \
  && dpkg -i /tmp/app.deb || apt-get -f install -y

5. Beta and nightly channels for testers​

# Beta testers
curl -L 'http://localhost:9000/apps/latest?app_name=SpaceExplorer&channel=beta&platform=darwin&arch=arm64&package=dmg&owner=admin'

# Nightly build enthusiasts
curl -L 'http://localhost:9000/apps/latest?app_name=SpaceExplorer&channel=nightly&platform=linux&arch=amd64&package=deb&owner=admin'

Notes and gotchas​

  • Channel is required once defined. If your app has channels, every /apps/latest request must include channel — otherwise the request is rejected.
  • owner is mandatory for access control; it must be your admin user name.
  • Package types are auto-detected from what's actually uploaded — you only get a dmg/deb/exe key if such a file exists for that platform/arch.
  • Redirect only fires for a single match. If your filters still leave multiple builds (e.g. both .deb and .rpm), you get JSON instead of a redirect — add package to force a direct download.
  • Use HTTPS in production and put faynoSync behind your own domain (e.g. updates.yourdomain.com) so download links stay stable and trusted.

What's Next? 🚀​

How to try faynoSync?​

  1. Follow the Getting Started guide:
    👉 https://faynosync.com/docs/getting-started

  2. Create your app using the REST API or web dashboard:
    📦 API Docs: https://faynosync.com/docs/api
    🖥️ Dashboard UI: https://github.com/ku9nov/faynoSync-dashboard

  3. Upload at least two versions of your application.

  4. Build a smart download link with /apps/latest.

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