OpenAI API vs Anthropic API
Frontier models: GPT-5, o-series reasoning, image, audio, embeddings
vs. API for Claude — frontier models for chat, tool use, agents, and long-context reasoning
Pricing tiers
OpenAI API
Free Tier (Trial)
$5 free credit for new accounts. Rate-limited.
Free
Pay-as-you-go
No monthly min. Per-token pricing by model.
$0 base (usage-based)
Usage Tiers (1-5)
Automatic tier promotion based on cumulative spend. Higher tiers = higher rate limits + new model access.
$0 base (usage-based)
Enterprise
Custom. Priority access, SLA, dedicated capacity.
Custom
Anthropic API
Opus 4.7 — usage
Input $5 / output $25 / cache-write $6.25 / cache-read $0.50 per 1M tokens. Batch = 50% off.
Custom
Sonnet 4.6 — usage
Input $3 / output $15 / cache-write $3.75 / cache-read $0.30 per 1M tokens. Batch = 50% off.
Custom
Haiku 4.5 — usage
Input $1 / output $5 / cache-write $1.25 / cache-read $0.10 per 1M tokens. Batch = 50% off.
Custom
Free-tier quotas head-to-head
Comparing free-tier on OpenAI API vs opus-4-7 on Anthropic API.
| Metric | OpenAI API | Anthropic API |
|---|---|---|
| discount batch | — | 50 % off |
Features
OpenAI API · 12 features
- Assistants API — Stateful assistants with tools, threads, file search.
- Batch API — 50% discount for async processing within 24h.
- Chat Completions API — Classic /v1/chat/completions endpoint.
- Files API — Upload docs for retrieval, fine-tuning, batch.
- Fine-Tuning — Supervised + DPO fine-tuning for GPT-4o, GPT-4.1, GPT-4o-mini.
- Function Calling — JSON-schema tool calling; parallel calls supported.
- Moderation — Safety classifier API (free).
- Prompt Caching — Auto-cache repeated prefixes; 50% cheaper cached hits.
- Realtime API — WebSocket streaming voice + text with low latency.
- Responses API — Stateful conversational API.
- Structured Outputs — Enforced JSON schema compliance.
- Vision — Image input for GPT models.
Anthropic API · 0 features
Developer interfaces
| Kind | OpenAI API | Anthropic API |
|---|---|---|
| CLI | — | Claude Code CLI |
| SDK | openai-dotnet, openai-go, openai-node, openai-python | Go SDK, Java SDK, Python SDK, Ruby SDK, TypeScript SDK (@anthropic-ai/sdk) |
| REST | OpenAI REST API | AWS Bedrock, Google Vertex AI, Microsoft Azure AI, REST API (Messages + Agents) |
| MCP | OpenAI MCP | — |
| OTHER | Realtime API (WebSocket) | — |
Staxly is an independent catalog of developer platforms. Outbound links to OpenAI API and Anthropic API are plain references to their official websites. Pricing is verified against vendor pages at publication time — reconfirm before buying.
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