The sustainable free tier. 72k+ GitHub stars, two distinct paths: free hosted tier with Kimi k2.5, or self-hosted with your own API keys.

Critical Distinction

OpenCode Zen (Free Tier): Kimi k2.5 + GLM 4.7 — NOT Claude Opus 4.5

OpenCode Self-Hosted (BYO API): Any model you have API keys for — includes Opus 4.5 (paid)

For free Opus 4.5 access, see Antigravity or Kiro instead.

Path A: OpenCode Zen (Free Tier)

What you get:

  • Kimi k2.5 - 76.8% SWE-bench, Claude 3.5 Sonnet-level
  • GLM 4.7 - 73.8% SWE-bench, chain-of-thought reasoning
  • No credit card required
  • Ongoing free access (rate limits apply)

Best for: Daily driver work, sustained free access, vision-to-code tasks (Kimi’s strength)

The value: Kimi k2.5 delivers ~80% of Opus 4.5’s performance with superior vision capabilities. At $0 instead of $200/month.

Path B: Self-Hosted (BYO API Keys)

What you get:

  • Any model from 75+ LLM providers
  • Claude Opus 4.5 (with your own Anthropic API key — $25/1M tokens)
  • Full control over data and configuration
  • No rate limits beyond what your API provider allows

Best for: High volume, proprietary code, existing API credits, specific model requirements

The cost: You pay for API usage. Opus 4.5 is $25/1M output tokens—no free tier here.

Quick Decision Matrix

SituationChooseOpus 4.5?Cost
Want free accessZenNo$0
Have API keysSelf-hostedYes (paid)API usage
Proprietary codeSelf-hostedOptionalAPI usage
High volumeSelf-hostedOptionalAPI usage
Need Opus 4.5 freeAntigravityYes (free)$0

The Setup

Zen (Easiest)

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npm install -g opencode
opencode --zen

Or visit opencode.ai

Self-Hosted

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npm install -g opencode

# Configure in ~/.config/opencode/config.json
{
  "provider": "anthropic",
  "model": "claude-opus-4-5",
  "api_key": "YOUR_API_KEY"
}

opencode

The Catch

Zen tier is beta: Currently in beta status. Free models (Kimi k2.5, GLM 4.7) are time-limited promotions for feedback collection, not permanent free tiers.

Rate limits: OpenCode uses a pay-as-you-go model with spending limits, not request-based limits. Exact numbers are not published by OpenCode (source). Not suitable for heavy production use.

Data usage: Free tier models may use data for training (verify current terms). Self-hosted keeps data private.

No Opus 4.5 on free tier: This is the main limitation. For free Opus 4.5, you need Antigravity or AMP Ad-Supported.

Last verified: January 30, 2026

Credit card: May be required for Zen signup even for free tier (billing details required).

Self-hosted complexity: You manage API keys, billing, and configuration.

Where Next

Need Opus 4.5 for free? → AMP Ad-Supported - Daily Opus 4.5 with non-intrusive ads (no CC required) → Antigravity - Free Opus 4.5 (no credit card, no ads)

Want VS Code integration? → Kilo Code - VS Code extension with 500+ models (promo ended, check current terms)

Need agentic workflows? → AMP - $10/day grant or ad-supported tier, autonomous editing

Ready to pay for Opus 4.5 API? → Claude Opus 4.5 Data - Pricing and limits

Why OpenCode Zen Wins

Kimi k2.5 is underrated:

  • 76.8% SWE-bench (80% of Opus 4.5’s 80.9%)
  • Native vision capabilities (mockups → working code)
  • 256K context window (larger than Claude’s 200K)
  • 100 sub-agent parallel execution

The math: Kimi API costs $3/1M tokens vs Opus 4.5’s $25/1M. If you ever upgrade from free, your money goes 8x further with Kimi.

OpenCode GitHub: https://github.com/opencode-ai/opencode Last verified: January 30, 2026. Rate limits: OpenCode uses pay-as-you-go with spending limits; exact numbers not published (source).