LLM gateway vs unified data API for AI agents

A common source of confusion in the agent infra stack: LLM gateways and unified data APIs look similar but solve different problems. This guide draws the line.

LLM gateway

An LLM gateway routes model inference — chat / completion / embedding calls — across one or more model providers (OpenAI, Anthropic, Google, open-source). It gives you:

  • One API key for many models
  • Fallback / retry across providers
  • Cost analytics and request logging
  • Caching, rate limiting, key management

Examples: OpenRouter, Portkey, LiteLLM, Helicone.

Unified data API for AI agents

A unified data API routes the tool calls your agent makes to read or write the outside world. It gives you:

  • One API key for many data sources (social, search, scrape, news)
  • One normalized request/response shape
  • An MCP server / OpenAPI spec so the agent can auto-discover capabilities
  • Pay-per-call billing across the whole catalog

UnifAPI fits this category — for public-data sources. For per-user OAuth into the user’s SaaS accounts (Gmail, Slack), see Composio.

Side-by-side

  LLM gateway Unified data API
What it routes Model inference Tool calls
Examples OpenRouter, Portkey, LiteLLM, Helicone UnifAPI, Composio (different scope)
Token cost surface Per-token model billing Per-call / per-credit
Used by Anyone calling an LLM Agents that touch the outside world

Why most production agents need both

A typical research agent looks like:

loop:
  plan = LLM(...)                        # ← LLM gateway
  results = web_search(plan.query)        # ← Unified data API
  pages   = [fetch_url(r.url) for r in ...]  # ← Unified data API
  answer  = LLM(plan, results, pages)    # ← LLM gateway

The two layers don’t compete — they sit on either side of the agent loop. Put differently:

LLM gateway is your model layer. Unified data API is your world layer.

Choosing UnifAPI

If you want one HTTP surface for the world side — Twitter, YouTube, TikTok, Google SERP, scrape, news — under one bearer key, with MCP and pay-per-call pricing, UnifAPI is built for that.

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