OpenAI API vs Google Gemini API
Frontier models: GPT-5, o-series reasoning, image, audio, embeddings
vs. Gemini 2.5 Pro, Flash, Flash-Lite — multimodal + 2M context
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
Google Gemini API
Free Tier (AI Studio)
Generous free tier with rate limits. Good for dev + prototyping. Data may be used to improve Google products.
Free
Paid API (Gemini API)
Pay-as-you-go per-token. Data NOT used for training.
$0 base (usage-based)
Vertex AI (GCP)
Enterprise deployment via Google Cloud. Same pricing structure + GCP features (IAM, VPC-SC, CMEK).
$0 base (usage-based)
Gemini Enterprise
Custom. Gemini 2.5 Deep Think model access + Google Workspace + Agentspace.
Custom
Free-tier quotas head-to-head
Comparing free-tier on OpenAI API vs free-tier on Google Gemini API.
| Metric | OpenAI API | Google Gemini API |
|---|---|---|
| No overlapping quota metrics for these tiers. | ||
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.
Google Gemini API · 11 features
- Batch API — 50% discount for async processing.
- Code Execution — Python code interpreter tool (sandboxed).
- Context Caching — Cache system instructions + tools for up to 90% savings.
- File API — Upload large files (up to 2 GB) for multimodal prompts.
- Function Calling — JSON schema-based tool calling. Parallel supported.
- generateContent API — Core generation endpoint.
- Grounding with Search — Augment answers with Google Search results. Fact-checked citations returned.
- Model Tuning — Supervised fine-tuning via AI Studio.
- Multimodal Live API — Bidirectional streaming voice + video (WebSocket).
- Safety Settings — Configurable thresholds for harm categories.
- streamGenerateContent — Streaming variant with SSE.
Developer interfaces
| Kind | OpenAI API | Google Gemini API |
|---|---|---|
| SDK | openai-dotnet, openai-go, openai-node, openai-python | @google/genai, google-genai-go, google-genai (Python) |
| REST | OpenAI REST API | Gemini REST API, Vertex AI Endpoint |
| MCP | OpenAI MCP | Gemini MCP |
| OTHER | Realtime API (WebSocket) | — |
Staxly is an independent catalog of developer platforms. Outbound links to OpenAI API and Google Gemini API are plain references to their official websites. Pricing is verified against vendor pages at publication time — reconfirm before buying.
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