AdMob mediation/bidding in Defold: are we limited to a small set of supported networks?

Questions
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We’ve recently integrated AdMob in our Defold project and enabled bidding/mediation. Right now we have these partners connected:

  • Meta Audience Network

  • ironSource

  • considering adding Unity Ads SDK (next)

I’m trying to understand what the real limitation is on Defold’s side.

From what I see, AdMob supports a bunch of networks, but in practice (especially with Defold native extensions) it feels like only a limited number of networks are “easy” to use because you need the correct mediation adapters (Android/iOS) included in the build.

So my questions:

  1. With Defold + AdMob, can we use any AdMob-supported mediation/bidding partner as long as it exists in AdMob, or are we effectively limited to the networks that are already packaged/maintained in the Defold AdMob extension?

  2. If we want to add a new network (e.g. Unity Ads), is the correct approach to rebuild/modify the native extension to include the required adapters (Gradle deps on Android / frameworks or pods on iOS)?

  3. Are there known platform-specific limitations (iOS vs Android) for adding extra mediation adapters in Defold builds?

  4. If someone has done this successfully: what’s the recommended setup today (AdMob-only mediation vs using ironSource as mediation, etc.)?

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The current AdMob extension only includes AdMob itself and doesn’t ship with any adapters.
I have a separate branch where I already started working on adding adapter support. If you give me a list of the adapters you need, I can look into them and make sure they work properly.

Yes, until we finish mediation we currently have in a separate branch as I mentioned above.

No, as far as I know there are no hard limitations, but some may appear during integration. Each ads adapter is a separate ads SDK with its own dependencies and potential issues. Building a large mediation setup with many networks usually involves 10 to 15 SDKs and hundreds of dependencies. Issues can arise unexpectedly, but they typically show up during the build process.

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admob mediation has this propositions:

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All i need for tests are: meta, ironsource, unity ads.

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Here is a separate Admob branch which supports mediation : GitHub - defold/extension-admob at mediation

On this branch it is possible on and off mediation networks using checkboxes in game.project - Admob section

I’m still testing it, but I know for sure that Charboost for android doesn’t without a workaround from this issue When an extension has a dependency on `androidx-multidex`, it conflicts with Defold SDK multidex. · Issue #385 · defold/extender · GitHub (should be added into appmanifest only in case you are going to use Charboost Android)

I’ll try to allocate time and finish most of the testing (and fixes if needed) the next week, but I’ll be happy to get help with testing. If you’ll have time for it and find something, feel free to report here: Add mediation support · Issue #31 · defold/extension-admob · GitHub

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I tested unity adapter. It works on the mediation branch.

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2026-01-23 17:14:55.558 15108-15108 UnityMediationAdapter   com.defold.adtest                    D  Unity Ads initialized successfully.
2026-01-23 17:14:55.564 15108-15108 AdmobJNI                com.defold.adtest                    D  Adapter name: com.google.android.gms.ads.MobileAds, Description: , Latency: 30
2026-01-23 17:14:55.564 15108-15108 AdmobJNI                com.defold.adtest                    D  Adapter name: com.google.ads.mediation.unity.UnityMediationAdapter, Description: , Latency: 1256
2026-01-23 17:14:55.567 15108-15167 defold                  com.defold.adtest                    D  DEBUG:SCRIPT: EVENT_COMPLETE: Initialization complete

Setting this up was not a pleasant experience, mainly because the SDK provides no feedback until everything is fully configured in the dashboard. For example, with Unity you must complete all the steps from this instruction: Integrate Unity Ads with mediation  |  Android  |  Google for Developers. It is impossible to test using Google’s test IDs; you have to use your own IDs. There are also no intermediate states like “adapter added but not initialized”. If something is missing, there is nothing in the logs or Ad Inspector, and if everything is done correctly, it simply reports that everything works fine.

For testing purposes, I added a checkbox in game.project -> admob.test_ads_in_debug that marks the device as a test device for the AdMob network.

Testing each adapter individually would take a lot of time, and I likely will not do it myself right now. This would require creating accounts in every ADS network, filling out company details, setting up projects, and passing any required reviews (e.g. IronSource).
That said, I expect that any adapter that builds should work. At the moment, only Chartboost fails to build, so I will remove it temporarily.

I recommend that you use the mediation branch. Select the adapters you need in the game.project under the admob section and carefully configure everything in the dashboard following the instructions above. If a checkbox is missing in this section, it means that the adapter is not required for bidding for that network (except for Chartboost, which I will remove until it is fixed on our side).

I will update this topic later with information about iOS support and when the PR with mediation support is merged.

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