Building a Coding Agent? Modal Sandboxes Shine, but E2B and Vercel Remain Unproven

pauliusztin · reddit · 2026-09-12

A course author building a coding agent from scratch shares hands-on experience integrating Modal Sandboxes into his agent harness for isolation, remote execution, and GPU access (running Qwen3.6 35B inference on an H200). He praises the easy integration, configuration, and fast spin-up, though he hasn't stress-tested long-running sessions or hundreds of parallel sandboxes in his eval harness.

He is soliciting production comparisons with alternatives like E2B, Cloudflare, and Vercel Sandboxes, arguing that sandboxes are among the most flexible pieces of infrastructure for building agents.

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