Hi GrowthBook team 👋, We are currently using the JS SDK on the frontend like this:

export const gbInstance = reactive(
  new GrowthBook({
    apiHost: "<https://cdn.growthbook.io>",
    clientKey: "sdk-xxx",
    ...
  })
)

But this generates a lot of CDN requests (We are in starter plan and just make the experiment online for 2 days, it becomes 12M requests 😢). To reduce requests, we’d like to add a backend cache layer. Our idea is to set up a custom backend endpoint like:

export const gbInstance = reactive(
  new GrowthBook({
    apiHost: "<https://custom-backend-endpoint/growthbook>",
    clientKey: "sdk-xxx",
  })
)

And implement the backend API:

GET <https://custom-backend-endpoint/growthbook/api/features/{sdk-key}>

This backend service would use the Ruby SDK to fetch feature settings from GrowthBook Cloud CDN, cache them, and then serve cached responses to the frontend.

def index
  render json: { status: 200, features: growthbook_features_json(params[:sdk_key]), dateUpdated: Time.current.iso8601 }
end

private

def growthbook_features_json(sdk_key)
  Rails.cache.fetch("growthbook_features_#{sdk_key}", expires_in: 1.hour) do
    features_repository = ::Growthbook::FeatureRepository.new(
      endpoint: "<https://cdn.growthbook.io/api/features/#{sdk_key}>",
      decryption_key: nil,
    )

    features_repository.fetch || {}
  end
end

👉 Is this architecture supported / recommended? 👉 Would the JS SDK work properly if

apiHost

points to our custom backend instead of the GrowthBook CDN? Thanks!

Caching the payload works fine

Thank you so much for the clarification!!! 🙏 For us, a short delay (e.g. up to an hour) is totally fine at this stage. We are still new to integrating GrowthBook, so as long as the solution works, that’s already great for us. We’ll start trying this approach. Really appreciate your help!

I'm actually not sure

Got it, thanks a lot Graham! 🙏 I’ll discuss this with my boss and see which direction we want to take. Appreciate your quick help!