Why Meta Chose Rust, Hack, Python, and C++ as Its Core Backend Languages

Meta, the parent company of Facebook, announced that its research and development division has officially approved four programming languages—Rust, Hack, Python, and C++—as the preferred choices for building its platform software.

The company emphasized that language decisions are made carefully, with each language selected for specific use cases and long‑term support for engineering teams.

Meta’s criteria for selecting a language include:

Support for core libraries, minimizing the burden of isolated services.

Security and privacy considerations.

Operational risk, ensuring rapid response to serious service issues.

Availability of expertise across the engineering organization.

Developer experience, such as IDE support, build speed, and debugging.

Rust is a system language originating from Mozilla and now governed by the Rust Foundation. Meta recommends Rust for performance‑critical backend services and CLI tools.

Hack is an open‑source, type‑safe variant of PHP that runs on the HHVM virtual machine. It is intended for business logic and relatively stateless applications on the Meta platform.

Python remains one of the most popular languages and is endorsed for data‑science, machine‑learning workloads, and Instagram‑related code.

C++ is a widely used general‑purpose language that Meta supports for performance‑sensitive backend services.

Meta also noted that other languages such as Java, Erlang, Haskell, and Go are considered “community‑supported” for specific use cases but are not officially endorsed.

The announcement highlighted Meta’s ongoing commitment to the Rust ecosystem, describing Rust as a “revenue‑safe” language and indicating long‑term support despite its learning curve.

In addition, a recent Everest Group report warned that companies operating in the metaverse will need to strengthen user trust and security, a concern that aligns with Meta’s broader VR ambitions and recent financial challenges.