Systems | Development | Analytics | API | Testing

The Multiplayer debugging agent is purpose-built for developers working with coding agents. It captures all the data observability tools miss and manages the whole process from bug identified to bug fixed. AI coding assistants are great at writing code. They are not great at fixing bugs in production and the reason is simple: they don’t have runtime visibility.

I’ve seen teams burn weeks untangling API messes that could have been avoided with a couple of days of upfront thinking. Endpoints named inconsistently, versioning added as an afterthought, error responses that just say "something failed" all of it traceable back to the same root cause. Nobody sat down and actually designed the API before building it. That distinction between building an API and designing one is what this guide is about.

Custom logging can technically capture everything, but in practice, it rarely does. Coverage degrades over time, external APIs get forgotten, and during incidents, you're left asking "did anyone log this?" instead of debugging. Automatic capture solves this. If you're a technical leader, there's a good chance your team is spending significant time on custom logging… and you might not even realize how much it's costing you in productivity and incomplete debugging data.

There's a common belief in the observability space: if you just collect more data, you'll have what you need to debug any issue. The reality is more frustrating: even with 100% unsampled observability, you're still missing critical debugging data. There's a common belief in the observability space: if you just collect more data, you'll have what you need to debug any issue. The reality is more frustrating: even with 100% unsampled observability, you're still missing critical debugging data.

Better specs and clearer task decomposition are a significant step forward. But specs and plans describe intentions. What AI agents also need is visibility into what systems actually do at runtime.

Architectural visualization, or archviz, has shifted rapidly from static 2D renders to immersive 3D experiences that have transformed how architects, designers, and developers communicate their vision. Using this technology, a development team can “walk” clients through hyper-realistic replicas of an office headquarters or residential complex well before ground is ever broken.

In 2025 we focused on a simple but ambitious goal: making debugging faster, less fragmented and less manual. Check out all our releases to make that possible. 2025 was a defining year for Multiplayer. We focused on a simple but ambitious goal: making debugging faster, less fragmented and less manual. That meant meeting developers where they were already working and capturing the right context at the right time.

Annotations are a way to draw, write, and comment directly on top of full-stack session recordings. Now, instead of sketching ideas in isolation, teams can mark up actual user sessions, highlighting specific UI elements, API calls, and backend traces that need attention. Whiteboarding tools are indispensable in system design for visually conveying concepts, ideas, and rough plans. They tap into our natural preference for visual learning.