Case Study: Sora - Shiguredo

Shiguredo is a product company based in Tokyo, Japan, that develops Sora, a WebRTC SFU (Selective Forwarding Unit) for real-time audio, video, and data. Sora powers everything from interactive meetings to large-scale live streams.

The Birth of Sora

Sora was launched in 2015, developed entirely in Erlang/OTP. From the very beginning, the team identified that Pure P2P WebRTC had practical limits for group calls and broadcasts. Anticipating the shift toward server-assisted WebRTC, Shiguredo started development early, positioning Sora ahead of the curve.

Team and Process

Sora has been developed by a fully remote team of several engineers, working with asynchronous stand-ups and thorough code reviews. The system itself is entirely written in Erlang/OTP, with Python + pytest used for end-to-end testing.

The Sora project makes extensive use of tools and libraries from the BEAM ecosystem and beyond, including:

• rebar3 and relx.
• ELP — used as a stable LSP.
• efmt — a fast, Rust-based formatter.
• RabbitMQ’s ra — a stable Raft library.
• gproc — a stable process-registry library (sponsored by Shiguredo).
• Cowboy / Gun — stable HTTP libraries (sponsored by Shiguredo).

Beyond their usage, Shiguredo actively contributes back to the community:

• Long-time sponsor of AsmJit, critical for native code generation.
• Sponsors of gproc and Cowboy via GitHub Sponsors.

While most of their own libraries remain closed-source, their sponsorship ensures that essential open source projects continue to thrive.

Overcoming Challenges

At the start of development, Erlang/OTP did not include DTLS (Datagram Transport Layer Security). To meet their requirements, the team implemented a custom Erlang-based DTLS stack, ensuring security and compliance from day one.

In its ten years of production use, Sora has experienced only one notable incident (a segmentation fault caused by a memory leak). Otherwise, the platform has delivered continuous service with zero unplanned downtime — a testament to the stability of Erlang/OTP and Shiguredo’s engineering practices.

For more details, visit the Sora official website.

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