Comparing free tiers across LLM API gateways for prototyping

Choosing a free tier LLM API gateways prototyping option determines how fast you can iterate before hitting paywalls. OpenRouter, Groq, and Cloudflare AI Gateway each offer a free entry point, but they differ sharply in model coverage, rate limits, and routing control.

The Contenders

OpenRouter is a multi-provider aggregator. You get one key and one endpoint that routes to 200+ models from Anthropic, OpenAI, Mistral, Meta, and others. Its free tier subsidizes a subset of open-weight models; everything else is per-token.

Groq is a single-vendor inference service built on custom LPU hardware. The free tier exposes Meta’s Llama families and Mistral variants through an OpenAI-compatible API, with aggressive rate caps but very low time-to-first-token.

Cloudflare AI Gateway is a proxy layer that sits in front of providers you configure (OpenAI, Anthropic, HuggingFace, etc.). The free tier includes a daily request allowance and caching, but you still need a provider key for the actual inference.

Dimensions That Matter for Prototyping

Capabilities

For prototyping, model diversity matters. OpenRouter wins on breadth: you can swap from a 7B test model to Claude 3.5 Sonnet behind the same call. Groq is narrow—fast but limited to models they host. Cloudflare adds no models itself; it inherits whatever you bind.

Price/Cost Model

OpenRouter’s free tier covers specific models indefinitely, but premium models bill per token with no monthly minimum. Groq’s free tier is unconditional but throttled; paid plans raise limits. Cloudflare’s gateway is free to use, but the underlying provider charges you—Cloudflare only meters requests on the gateway layer.

Latency/Throughput

Groq is consistently sub-second for small prompts. OpenRouter latency tracks the upstream provider; a free open-weight model may run on shared GPUs with 1–3s lags. Cloudflare injects a proxy hop (typically <50ms) but inherits provider latency.

Ergonomics

All three speak OpenAI-compatible JSON. Differences appear in header semantics:

from openai import OpenAI

# OpenRouter
or_client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key="sk-or-xxx"
)
# Groq
groq_client = OpenAI(
    base_url="https://api.groq.com/openai/v1",
    api_key="gsk_xxx"
)
# Cloudflare (via worker route)
cf_client = OpenAI(
    base_url="https://gateway.ai.cloudflare.com/v1/ACCT/GW/openai",
    api_key="sk-xxx"
)

Some gateways such as n4n.ai honor client routing directives and forward provider cache-control hints, letting you pin a provider or leverage prompt caching across fallback paths. That level of control is absent on Groq and only partial on Cloudflare.

Ecosystem

OpenRouter has the largest model catalog and community rankings. Groq’s ecosystem is hardware-locked but growing. Cloudflare’s value is its edge network, logs, and caching rather than model selection.

Limits

Free tiers impose hard ceilings. OpenRouter limits concurrent requests per model on free accounts. Groq enforces per-minute token and request caps. Cloudflare’s free gateway tier caps daily requests; exceed it and calls 429.

Comparison Table

Calling Them: Minimal Snippets

OpenRouter free model:

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OR_KEY" \
  -d '{"model":"mistralai/mistral-7b-instruct","messages":[{"role":"user","content":"ping"}]}'

Groq:

curl https://api.groq.com/openai/v1/chat/completions \
  -H "Authorization: Bearer $GROQ_KEY" \
  -d '{"model":"llama3-8b-8192","messages":[{"role":"user","content":"ping"}]}'

Cloudflare (assuming gateway bound to OpenAI):

curl https://gateway.ai.cloudflare.com/v1/$ACCT/$GW/openai/v1/chat/completions \
  -H "Authorization: Bearer $OA_KEY" \
  -d '{"model":"gpt-4o-mini","messages":[{"role":"user","content":"ping"}]}'

Which to Choose

Use OpenRouter if you need to A/B test many model families without managing multiple keys, and you want a free path that scales into paid premium models via the same client. The free tier LLM API gateways prototyping experience here is the most flexible for product discovery.

Use Groq if your prototype is latency-sensitive (voice, real-time agents) and you can live with Llama/Mistral class output. The free tier LLM API gateways prototyping loop is tightest when you don’t need provider diversity.

Use Cloudflare AI Gateway if you already run on Workers, need request logging, caching, and retry logic at the edge, and have a provider key. It is the best free tier LLM API gateways prototyping choice for infra control, not model access.

For most indie developers starting cold, OpenRouter gives the widest runway; for demos that must feel instant, Groq wins; for production-bound architectures with existing Cloudflare footprint, the gateway tier is a no-brainer.