Network

Outbound Connections

OpenCode connects to external services for several purposes:

Destination	Purpose	Required	Configurable
LLM provider APIs	Model inference and completion	Yes	Yes
OpenCode Zen / Go	Authentication and licensing	For licensed features	No
Auto-update endpoint	Version update checks	No	Yes
Remote config host	.well-known/opencode config	No	Yes
Web content URLs	Tools that fetch web pages	Conditional	Yes
mDNS multicast	Local network discovery	No	Yes
Plugin registries (npm)	Plugin installation	Conditional	No

LLM Provider APIs

OpenCode connects to the API endpoints configured in your provider settings. Common endpoints include:

https://api.anthropic.com/v1/
https://api.openai.com/v1/
https://generativelanguage.googleapis.com/v1/
https://api.groq.com/openai/v1/
https://api.together.xyz/v1/
https://api.fireworks.ai/inference/v1/
https://api.mistral.ai/v1/
https://api.cohere.com/v1/

For self-hosted models, configure the base URL in opencode.json:

{
  "provider": {
    "ollama": {
      "baseURL": "http://localhost:11434/api"
    },
    "lm-studio": {
      "baseURL": "http://localhost:1234/v1"
    }
  }
}

tip

Verify your provider's base URL by testing with curl before configuring it in OpenCode.

OpenCode Zen / Go

Authentication and licensed feature access require connectivity to OpenCode's auth services. These connections use HTTPS and transmit only authentication tokens and basic version information.

Auto-Update

By default, OpenCode checks for updates periodically. This behavior can be controlled:

{
  "autoupdate": false
}

Set to "notify" to check but not auto-install:

{
  "autoupdate": "notify"
}

Remote Configuration

OpenCode can fetch remote configuration from https://<host>/.well-known/opencode when supported by the configured provider or when explicitly configured. This enables organization-wide defaults for:

• Allowed models
• Provider configurations
• Permission policies
• Agent definitions

Remote config is fetched once at startup and cached. If the endpoint is unreachable, the local configuration is used without error.

Proxy Support

OpenCode respects standard system proxy environment variables:

HTTP_PROXY=http://proxy.corp.example:8080
HTTPS_PROXY=http://proxy.corp.example:8080
NO_PROXY=localhost,127.0.0.1,.internal.example

Both uppercase and lowercase variants are recognized (HTTP_PROXY, http_proxy, etc.). Set these in your shell profile or systemd service file:

export HTTP_PROXY="http://proxy.company.com:3128"
export HTTPS_PROXY="http://proxy.company.com:3128"
export NO_PROXY="127.0.0.1,localhost,.local"

tip

If behind a corporate proxy, ensure NO_PROXY includes internal and local addresses to avoid routing loops.

mDNS Discovery

When the server mode has mdns enabled, OpenCode advertises its presence using multicast DNS. This requires:

• UDP port 5353 for mDNS traffic
• Multicast group 224.0.0.251 (IPv4) or ff02::fb (IPv6)
• Network segment supporting multicast (may not work across VPNs or cloud VPCs without configuration)

Disable mDNS in environments where multicast is restricted:

{
  "server": {
    "mdns": false
  }
}

CORS

In server mode with web UI or browser-based clients, configure Cross-Origin Resource Sharing:

{
  "server": {
    "cors": [
      "http://localhost:5173",
      "https://opencode.internal.example.com"
    ]
  }
}

CORS headers are only sent for origins that exactly match an entry in the list. Wildcard origins (*) are not supported for security reasons.

Firewall Rules

If you operate behind a corporate firewall, allow outbound HTTPS (TCP/443) to your LLM provider endpoints and the OpenCode auth services. For mDNS, allow UDP/5353 multicast on the local network segment.

Minimal Allowlist

For the most restricted environments, you only need:

• HTTPS outbound to your LLM provider's API endpoint(s)
• HTTPS outbound to api.opencode.ai (or whatever the auth domain is)

Everything else (auto-updates, remote config, web tools) is optional and can be disabled.

Offline Mode

Troubleshooting Network Issues

# Check connectivity to provider
curl -v https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{"model":"claude-sonnet-4-20250514","max_tokens":10,"messages":[{"role":"user","content":"hi"}]}'

# Verify proxy configuration
echo $HTTP_PROXY
echo $HTTPS_PROXY
echo $NO_PROXY

# Test mDNS resolution
dns-sd -B _opencode._tcp local

# Check OpenCode auth status
opencode auth list