Sandboxed Code Execution as an API
OnlineCompiler.io is a sandboxed code execution platform for 12 languages, with a REST API, WebSocket support, an embeddable widget, and MCP support for AI agents.
Category
Developer Infrastructure + AI-Ready Tooling
Project Type
Live API platform at onlinecompiler.io
Audience
Developers, edtech platforms and AI agents
The Problem
Running arbitrary user code is a problem most teams would rather not own. Doing it safely means container isolation, resource limits, and careful handling of anything that touches the network or filesystem, which is a lot of infrastructure to build for what is usually a small product feature.
OnlineCompiler.io turns that into an API call. Education platforms, documentation sites, and AI agents can execute code without operating the sandbox themselves.
What We Built
- sandboxed execution across 12 programming languages
- REST API for synchronous execution
- WebSocket support for streaming output
- embeddable widget for documentation and learning sites
- MCP support so AI agents can execute code as a tool
- resource limits and execution timeouts
Relevant Service Lanes
Executing untrusted code as a service means the security model is the product. Every design decision follows from containing what runs.
Why This Was More Than a Code Runner
Executing untrusted code as a service means the security model is the product. Every design decision follows from containing what runs.
isolating untrusted code without making cold starts unusable
streaming output over WebSockets while keeping the sandbox sealed
supporting 12 language toolchains with predictable behaviour
exposing execution to AI agents through MCP safely
keeping per-execution cost low enough for an API product
Technology Stack
Outcome
- live in production at onlinecompiler.io
- supports 12 languages behind one API
- MCP support makes it directly usable as an AI agent tool
- embeddable widget extends it beyond the API surface
Need Sandboxed Execution or a Developer API?
If you are planning a similar platform, MicroPyramid senior engineers can scope it, build it, and support it in production.
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