LangChain vs OpenRouter

LangChain

OpenRouter

LangChain · 18 features

• Agents — Tool-using agents with reasoning loops.
• Chains (LCEL) — LangChain Expression Language — pipe primitives into chains.
• Checkpointers (LangGraph) — Persist agent state to SQL, Mongo, Redis, Postgres.
• Document Loaders — 150+ loaders for PDF, HTML, Notion, Google Drive, S3, GitHub, etc.
• Human-in-the-loop — Pause agent for approval, then resume.
• LangGraph — Stateful graph-based agent runtime. Durable, replayable, human-in-the-loop.
• LangGraph Platform — Managed hosting for LangGraph agents with state persistence.
• LangGraph Studio — Desktop IDE for debugging agent graphs.
• LangServe — Deploy chains as FastAPI endpoints.
• Memory — Buffer, summary, entity, vector memory stores.
• Output Parsers — Structured JSON, Pydantic schemas, function calling.
• Prompt Templates — Templating + partial filling + output parsers.
• RAG (Retrieval-Augmented Generation) — Standard patterns + 50+ retrievers.
• Streaming — First-class streaming at every layer.
• Subgraphs — Compose agent graphs hierarchically.
• Text Splitters — Recursive, token, semantic splitters for chunking.
• Tools — 400+ pre-built tools (web search, code, databases, APIs).
• Vector Store Integrations — 60+ vector DBs (Pinecone, Chroma, Weaviate, PGVector, Qdrant, Milvus).

OpenRouter · 15 features

• 300+ Models — Claude, GPT, Gemini, Llama, Mistral, Qwen, DeepSeek, Cohere, Grok + open-source.
• 60+ Providers — Anthropic, OpenAI, Google, Together, Fireworks, Groq, DeepInfra, Replicate, etc.
• Auto Fallback — Automatic retry to backup provider on failure.
• Bring Your Own Key — Use your own provider keys → pay providers directly + no platform fee.
• Credit System — Prepay credits via card, crypto, or bank.
• Data Retention Controls — Opt-out of training/retention per provider.
• Free Models Tier — 25+ models available at $0 (limited rate).
• Prompt Caching — Automatic cache for identical prefixes (provider-dependent).
• Provider Preferences — Pin preferred providers per request or default.
• Rankings & Stats — Public leaderboard of most-used models.
• Regional Routing — Route requests to specific geographic regions.
• Streaming — SSE + partial completions.
• Structured Outputs — JSON-mode + JSON schema across supporting models.
• Tool Use / Function Calling — Unified tool calling across providers.
• Unified OpenAI-Compat API — Same endpoint for every model + provider.