OpenAI API vs LlamaIndex
Frontier models: GPT-5, o-series reasoning, image, audio, embeddings
vs. Data framework for LLMs — RAG-first with LlamaCloud + LlamaParse
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
LlamaIndex
OSS (MIT)
MIT-licensed core. Python + TypeScript. Free forever.
$0 base (usage-based)
LlamaCloud — Free
Free tier of LlamaCloud. 1,000 pages/day via LlamaParse. Basic indexing.
Free
LlamaCloud — Paid
Pay-per-page parsing + usage-based indexing. $0.003 per page (Fast mode).
$0 base (usage-based)
LlamaCloud Enterprise
Custom. SSO, SOC2, higher rate limits, private index hosting.
Custom
Free-tier quotas head-to-head
Comparing free-tier on OpenAI API vs oss on LlamaIndex.
| Metric | OpenAI API | LlamaIndex |
|---|---|---|
| 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.
LlamaIndex · 16 features
- Agents — Agent patterns: ReAct, function-calling, multi-agent workflows.
- Document Readers — 200+ readers for PDF, web, Google Drive, SharePoint, Notion, S3, Slack.
- Evaluations — Built-in eval framework: faithfulness, context precision/recall.
- LlamaCloud — Managed indexing + retrieval platform. File connectors, auto-chunking, retrieval…
- LlamaExtract — Schema-based structured extraction from unstructured docs.
- LlamaHub — Community marketplace of readers, tools, prompts.
- LlamaParse — Best-in-class PDF + complex document parser. Tables, math, layout preserved.
- Multimodal — Image + text models, image retrieval.
- Node Parsers — Document chunkers: token, sentence, semantic, hierarchical.
- Observability (OpenLLMetry) — OTel-based tracing baked in.
- Property Graph — Graph-based RAG (knowledge graphs from unstructured data).
- Query Engines — Retrieval + response synthesis combos — router, sub-question, tree, etc.
- RAG — End-to-end RAG patterns: ingest → index → retrieve → synthesize.
- Tools — 50+ pre-built tool integrations.
- Vector Store Integrations — 50+ vector DB integrations.
- Workflows — Event-driven agent workflows (AgentWorkflow).
Developer interfaces
| Kind | OpenAI API | LlamaIndex |
|---|---|---|
| SDK | openai-dotnet, openai-go, openai-node, openai-python | llama-index (Python), llamaindex (TS) |
| REST | OpenAI REST API | LlamaCloud API, LlamaParse API |
| MCP | OpenAI MCP | LlamaIndex MCP |
| OTHER | Realtime API (WebSocket) | — |
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