A script that tests whether your network breaks large uploads to the Claude API (github.com)

A new script called "claude-net-check.js" has been released to diagnose network issues affecting large uploads to the Claude API. Users encountering API errors such as EPROTO, ECONNRESET, or TLSV1_ALERT_DECODE_ERROR can utilize this tool to determine if the problem lies within their network path rather than with the Claude Code itself. The script, which requires only Node.js and no additional dependencies, sends filler data in various sizes (ranging from 1 KB to 1 MB) to the API and analyzes the success rate of these uploads to identify disruptions in the TLS connection. This development is significant for the AI/ML community, particularly for developers relying on the Claude API, as it offers a straightforward method to troubleshoot network-related issues that impact large data transfers. By revealing whether small uploads succeed while larger ones fail, the script highlights potential flaws in interim network products like firewalls, VPNs, or proxies that may interfere with secure connections. The ability to systematically test different network configurations enhances troubleshooting efficiency, and the tool’s MIT licensing ensures accessibility for users to modify it as needed.