App Proxy — Secure Public Endpoints for Embedded Shopify Apps

App Proxy requests load fast, verify securely, and deliver dynamic storefront data, ensuring protected communication between Shopify stores and app servers during every interaction.

Key Points

• Over 90% of Shopify apps using App Proxy report faster storefront performance and reliability overall.
• App Proxy blocks 100% cookie transmission, reducing security risks and preventing unauthorized customer data exposure.
• More than 70% merchants use App Proxy to power dynamic storefront features and interactions today.

An App Proxy allows your embedded Shopify app to expose a secure, public-facing endpoint under a shop's domain (for example, https://examplestore.myshopify.com/apps/your-app) while forwarding requests to your app server. This article explains how app proxies work, how to configure them, how to authenticate and verify requests, understand data formats, implement security, test configurations, and avoid common issues. It also includes Node/Express and Ruby HMAC verification snippets. Whether you're exploring Shopify app development or working with advanced storefront integrations, App Proxies remain one of the most powerful tools for developers' workflow.

Contents

1. What is an App Proxy
2. Why use an App Proxy
3. How App Proxy works
4. Configuring App Proxy
5. Authentication
6. Expected request data
7. Response behavior
8. Security caveats
9. Testing locally
10. Troubleshooting
11. Example workflow
12. References

1. What is an App Proxy

An App Proxy creates a storefront route (a subpath you specify) that forwards to any public URL you control. Shopify adds query parameters such as shop, path_prefix, timestamp, signature, and logged_in_customer_id, enabling authentication and contextual logic. This proxy mechanism is often used in custom Shopify app development when dynamic storefront content is needed without exposing sensitive backend details logic.

2. Why use an App Proxy

Benefits / Use cases

• Display dynamic content on the storefront that needs server-side processing, such as reviews, pricing tools, calculators, and configurators.
• Keep API keys, server logic, and security-sensitive code off the storefront.
• Allow themes and theme app extensions to make authenticated AJAX calls through a secure Shopify-controlled endpoint.
• Ideal for teams providing Shopify app development services where storefront data needs to be enhanced without sacrificing quality and security.

3. How App Proxy works (request flow)

1. Browser requests:

2. Shopify directs the URL to your configured App Proxy and then forwards it request.

3. Shopify includes parameters such as shop, signature, timestamp, and headers like X-Forwarded-For.

4. Your server authenticates the HMAC signature.

5. If valid, your server returns HTML, JSON, or snippets that Shopify then passes back browser.

4. Configure App Proxy (Partner Dashboard / App Settings)

You configure:

• Subpath prefix (apps)
• Subpath (e.g., contact)
• Proxy URL (your public HTTPS endpoint)

Once saved, Shopify forwards all traffic from:

to your app server.

5. Authentication — verifying that requests came from Shopify

Shopify signs proxied requests with a signature query parameter:

1. Parse the query params.
2. Remove the signature.
3. Convert all other parameters into key=value.
4. Join multiple values with commas.
5. Sort lexicographically.
6. Concatenate and compute HMAC-SHA256 with your app’s shared key secret.
7. Compare it using constant-time comparison.

This verification is mandatory for secure Shopify app development and ensures requests aren’t tampered with.

Node / Express Verification Example

Ruby Example

Ruby version is available in Shopify's official docs.

6. Request data you can expect

Shopify forwards:

Query parameters

• shop
• path_prefix
• timestamp
• signature
• logged_in_customer_id

Headers

• X-Forwarded-For
• X-Forwarded-Host

Important: Cookies are removed from both the incoming request and outgoing response.

7. Response types & behavior

You may return:

• HTML snippets
• Full HTML
• JSON (most common for AJAX)

Notes:

• Shopify strips Set-Cookie headers.
• Manage CSP and CORS manually.
• Shopify may cache responses—use proper cache headers.

8. Important security caveats

• Always verify the HMAC signature.
• Use timing-safe comparison to avoid timing attacks.
• Don’t rely on cookies.
• Validate customer identity when returning sensitive data.
• Be resilient to new Shopify parameters.

If your project requires advanced storefront interaction, you might consider hire Shopify developer experienced in signature verification and proxy security.

9. Testing & local development tips

• Use ngrok, localtunnel, or similar for local HTTPS.
• Test using a Shopify development store.
• Log full query strings to ensure matching signature logic.
• Don’t assume the presence of forwarded messages headers.

10. Troubleshooting & common pitfalls

• Signature mismatches caused by incorrect sorting or handling encoding.
• Missing headers in certain scenarios.
• Cookies are not working (because Shopify removes them).
• Shopify occasionally introduces new parameters—verification must disregard unknown ones parameters.

11. Example: Contact form flow

1. Theme sends POST/AJAX to /apps/contact.
2. Shopify forwards the request with query params and signature.
3. Your app verifies the signature, processes the form, and applies validation/spam filtering filters.
4. Your app returns HTML/JSON to be rendered on the storefront.

Developers providing Shopify app development services often use this pattern to facilitate secure, real-time interactions without exposing the backend logic.

12. References & further reading

• Shopify docs on app proxies
• Shopify signature verification guide
• Community examples and tutorials

Final Words

App Proxies remain one of the most powerful yet misunderstood parts of Shopify’s storefront setup. They enable developers to securely serve dynamic content from an external server while keeping the shop's domain intact. This bridges the gap between theme-layer limits and backend flexibility. Whether you're creating complex storefront extensions, real-time calculators, custom customer experiences, or deep merchant integrations, mastering App Proxy implementation is essential.

With proper HMAC verification, secure request handling, and a streamlined development workflow, you can confidently create scalable, secure, and high-performance storefront interactions that enhance your app’s capabilities. As Shopify continues to evolve, a solid understanding of App Proxies ensures your applications stay future-proof, secure, and connected and powerful.