Free LLM API Endpoints & OpenAI-Compatible Inference Gateways

Building autonomous coding agents, continuous integration pull-request reviewers, log anomaly classifiers, and multi-tenant RAG pipelines does not require burning thousands of dollars per month on single-vendor inference bills. Across the 2026 AI hardware and cloud ecosystem, custom silicon manufacturers (Groq, Cerebras, SambaNova, NVIDIA), hyperscalers (Google AI Studio, Cloudflare Workers AI), frontier labs (Mistral AI, Cohere), and aggregation routers (OpenRouter, Hugging Face Inference Router) expose generous, no-credit-card free tiers speaking the standard OpenAI /v1/chat/completions wire protocol.

When a backend service relies on a single free endpoint, hitting a per-minute token ceiling (HTTP 429 Too Many Requests) stalls the entire pipeline. However, when you unify eight to twelve independent free-tier providers behind an automatic circuit-breaking failover router, your infrastructure unlocks over 2,500,000+ free tokens per day, 15,000+ daily requests, and hardware-accelerated throughput reaching 2,000 tokens per second at zero marginal cost. This technical reference documents every active free LLM API endpoint on the internet, including exact base URLs, model identifiers, rate-limit ceilings, data-retention caveats, ready-to-run curl probes, and a production TypeScript failover client.

Master Comparison Matrix: 12 Active Free LLM API Gateways (2026)

The specification table below compares all verified cloud inference providers offering persistent free tiers or recurring daily/monthly allowances without mandatory credit card billing:

Deep-Dive Provider Specifications & Endpoint Verification

Below are the exact architectural parameters, rate-limit nuances, and curl verification commands for each primary free tier.

1. Google AI Studio (Gemini Developer API)

Google AI Studio (`aistudio.google.com`) offers the most generous context window in the industry: a full 1,000,000-token context window on the free tier without requiring a Google Cloud billing account. In addition to its native generateContent REST interface, Google maintains a first-class OpenAI compatibility layer supporting tool calling, structured JSON schema outputs, and streaming Server-Sent Events (SSE).

• OpenAI Chat Completions Endpoint: POST https://generativelanguage.googleapis.com/v1beta/openai/chat/completions
• Native REST Endpoint: POST https://generativelanguage.googleapis.com/v1beta/models/{model}:generateContent?key=$GEMINI_API_KEY
• Recommended Free Models: gemini-2.5-flash (primary reasoning & multimodal workhorse), gemini-2.5-flash-lite (high-frequency classification), gemini-2.5-pro (complex architectural debugging), and text-embedding-004 (vector indexing).

curl -sS https://generativelanguage.googleapis.com/v1beta/openai/chat/completions \
  -H "Authorization: Bearer $GEMINI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-2.5-flash",
    "messages": [
      {"role": "system", "content": "You are a senior systems architect."},
      {"role": "user", "content": "List three advantages of epoll over select in Linux."}
    ],
    "temperature": 0.2
  }'

2. Groq Cloud (Deterministic LPU Inference Engine)

Groq replaces conventional HBM-bound GPU clusters with custom SRAM-based Language Processing Units (LPUs), streaming llama-3.3-70b-versatile at 300+ tokens/sec and llama-3.1-8b-instant at over 800 tokens/sec. On Groq's free tier, the primary engineering constraint is Tokens Per Minute (TPM) (typically 6,000 to 30,000 TPM depending on the model) rather than daily request count. Keep system prompts compact to avoid bursts exceeding the 60-second sliding TPM window.

• OpenAI Chat Completions Endpoint: POST https://api.groq.com/openai/v1/chat/completions
• OpenAI Audio Whisper Endpoint: POST https://api.groq.com/openai/v1/audio/transcriptions (supports free whisper-large-v3-turbo speech-to-text)
• Flagship Free Models: llama-3.3-70b-versatile (1,000 RPD), llama-3.1-8b-instant (14,400 RPD), deepseek-r1-distill-llama-70b, and qwen-qwq-32b.

curl -sS https://api.groq.com/openai/v1/chat/completions \
  -H "Authorization: Bearer $GROQ_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "llama-3.3-70b-versatile",
    "messages": [
      {"role": "user", "content": "Explain why SRAM eliminates memory bandwidth bottlenecks during autoregressive token decoding."}
    ]
  }'

3. Cerebras Cloud (Wafer-Scale Engine WSE-3)

Cerebras Cloud runs inference on the WSE-3 wafer-scale processor containing 4 trillion transistors and 44 GB of on-chip SRAM. Its free developer tier grants 1,000,000 free tokens per day, 60,000 TPM, and 30 RPM at roughly 2,000 tokens/sec, making it the fastest and highest-volume free code generation endpoint available.

• OpenAI Chat Completions Endpoint: POST https://api.cerebras.ai/v1/chat/completions
• Flagship Free Models: llama-3.3-70b, llama-3.1-8b, qwen-3-32b, and deepseek-r1-distill-llama-70b.

curl -sS https://api.cerebras.ai/v1/chat/completions \
  -H "Authorization: Bearer $CEREBRAS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "llama-3.3-70b",
    "messages": [
      {"role": "user", "content": "Write a lock-free ring buffer index calculation in C."}
    ]
  }'

4. OpenRouter (:free Model Pool & Meta-Router)

OpenRouter maintains a live catalog of more than 25 zero-cost models suffixed with :free (such as deepseek/deepseek-r1:free, deepseek/deepseek-chat-v3-0324:free, meta-llama/llama-3.3-70b-instruct:free, and qwen/qwen3-235b-a22b:free), plus the special meta-model openrouter/free that automatically dispatches requests to whichever free upstream provider currently has the lowest queue latency.

• OpenAI Chat Completions Endpoint: POST https://openrouter.ai/api/v1/chat/completions
• Programmatic Free Model Discovery: Poll GET https://openrouter.ai/api/v1/models and filter entries where pricing.prompt === "0" and pricing.completion === "0".
• The $10 Credit Tier Multiplier: Pure $0 accounts are capped at 20 RPM and 50 requests/day on :free models. However, depositing a one-time $10 credit permanently unlocks 1,000 requests/day on all :free models—and because :free models cost $0.00/token, your $10 balance is never spent.

curl -sS https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "HTTP-Referer: https://robertscreations.com" \
  -H "X-Title: RobertsCreations Inference Router" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "deepseek/deepseek-r1:free",
    "models": [
      "deepseek/deepseek-r1:free",
      "meta-llama/llama-3.3-70b-instruct:free",
      "google/gemma-3-27b-it:free"
    ],
    "messages": [
      {"role": "user", "content": "Derive the time complexity of consistent hashing with virtual nodes."}
    ]
  }'

5. Mistral AI (La Plateforme Experiment Tier & Codestral)

Mistral AI provides two distinct free pathways on console.mistral.ai after completing SMS verification: the general Experiment plan at https://api.mistral.ai/v1 (1 RPS / 60 RPM, 500,000 TPM) and the dedicated Codestral code-generation endpoint at https://codestral.mistral.ai/v1.

curl -sS https://api.mistral.ai/v1/chat/completions \
  -H "Authorization: Bearer $MISTRAL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "codestral-latest",
    "messages": [
      {"role": "user", "content": "Write a TypeScript Express middleware that validates HMAC-SHA256 webhook signatures."}
    ]
  }'

6. Cloudflare Workers AI & Hugging Face Inference Router

Cloudflare Workers AI allocates 10,000 free Neurons per day (resetting at 00:00 UTC) across every Cloudflare account without requiring a payment method. Using its OpenAI-compatible path (https://api.cloudflare.com/client/v4/accounts/{ACCOUNT_ID}/ai/v1/chat/completions), you can run @cf/meta/llama-3.3-70b-instruct-fp8-fast, @cf/deepseek-ai/deepseek-r1-distill-qwen-32b, and @cf/baai/bge-m3 embeddings at the network edge with strict data isolation.

Similarly, the Hugging Face Inference Router (https://router.huggingface.co/v1/chat/completions) replaces the legacy api-inference.huggingface.co endpoint and allows developers to append dynamic routing policies directly to the model identifier—such as Qwen/Qwen2.5-72B-Instruct:fastest or deepseek-ai/DeepSeek-V3:cheapest—using free monthly starter credits included with every hf_... token.

Local Zero-Cost OpenAI-Compatible Fallbacks

For air-gapped workloads, PII/HIPAA/financial processing, or final-tier fallback when all cloud rate limits are saturated, run a local OpenAI-compatible server on workstation or server GPUs:

Production Implementation: TypeScript Multi-Provider Free LLM Failover Router

To achieve 99.99% availability across free tiers without paying a cent, wrap the providers in a deterministic failover loop. When an upstream gateway returns HTTP 429 Too Many Requests, HTTP 503, or times out, the router immediately fails over to the next provider in the chain:

export interface ChatMessage {
  role: 'system' | 'user' | 'assistant';
  content: string;
}

export interface FreeProviderEndpoint {
  name: string;
  baseUrl: string;
  apiKeyEnv: string;
  model: string;
  timeoutMs: number;
}

export const FREE_LLM_FAILOVER_CHAIN: FreeProviderEndpoint[] = [
  {
    name: 'Cerebras-WSE3',
    baseUrl: 'https://api.cerebras.ai/v1',
    apiKeyEnv: 'CEREBRAS_API_KEY',
    model: 'llama-3.3-70b',
    timeoutMs: 12000,
  },
  {
    name: 'Groq-LPU',
    baseUrl: 'https://api.groq.com/openai/v1',
    apiKeyEnv: 'GROQ_API_KEY',
    model: 'llama-3.3-70b-versatile',
    timeoutMs: 12000,
  },
  {
    name: 'Google-Gemini-Studio',
    baseUrl: 'https://generativelanguage.googleapis.com/v1beta/openai',
    apiKeyEnv: 'GEMINI_API_KEY',
    model: 'gemini-2.5-flash',
    timeoutMs: 20000,
  },
  {
    name: 'OpenRouter-Free-Pool',
    baseUrl: 'https://openrouter.ai/api/v1',
    apiKeyEnv: 'OPENROUTER_API_KEY',
    model: 'deepseek/deepseek-r1:free',
    timeoutMs: 25000,
  },
  {
    name: 'Mistral-LaPlateforme',
    baseUrl: 'https://api.mistral.ai/v1',
    apiKeyEnv: 'MISTRAL_API_KEY',
    model: 'mistral-small-latest',
    timeoutMs: 20000,
  },
  {
    name: 'HuggingFace-Router',
    baseUrl: 'https://router.huggingface.co/v1',
    apiKeyEnv: 'HF_TOKEN',
    model: 'Qwen/Qwen2.5-72B-Instruct:fastest',
    timeoutMs: 20000,
  },
  {
    name: 'Local-Ollama-Fallback',
    baseUrl: 'http://127.0.0.1:11434/v1',
    apiKeyEnv: 'OLLAMA_API_KEY',
    model: 'qwen2.5-coder:14b',
    timeoutMs: 30000,
  },
];

export async function dispatchFreeChatCompletion(
  messages: ChatMessage[],
  temperature = 0.2
): Promise<{ provider: string; model: string; content: string }> {
  const diagnostics: string[] = [];

  for (const endpoint of FREE_LLM_FAILOVER_CHAIN) {
    const apiKey =
      process.env[endpoint.apiKeyEnv] ||
      (endpoint.name === 'Local-Ollama-Fallback' ? 'ollama' : '');
    if (!apiKey) continue;

    const controller = new AbortController();
    const timer = setTimeout(() => controller.abort(), endpoint.timeoutMs);

    try {
      const res = await fetch(`${endpoint.baseUrl}/chat/completions`, {
        method: 'POST',
        signal: controller.signal,
        headers: {
          Authorization: `Bearer ${apiKey}`,
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({
          model: endpoint.model,
          messages,
          temperature,
        }),
      });

      if (!res.ok) {
        diagnostics.push(`${endpoint.name}: HTTP ${res.status}`);
        continue;
      }

      const payload = (await res.json()) as {
        choices?: Array<{ message?: { content?: string } }>;
      };
      const text = payload.choices?.[0]?.message?.content?.trim();
      if (text) {
        return {
          provider: endpoint.name,
          model: endpoint.model,
          content: text,
        };
      }
    } catch (err) {
      diagnostics.push(`${endpoint.name}: ${(err as Error).message}`);
    } finally {
      clearTimeout(timer);
    }
  }

  throw new Error(`Free LLM failover chain exhausted: ${diagnostics.join(' | ')}`);
}

Frequently Asked Engineering Questions

Which free LLM API endpoint offers the highest daily token limit without a credit card?

Cerebras Cloud currently provides the largest free daily token allowance at 1,000,000 tokens per day (30 RPM, 60,000 TPM) on llama-3.3-70b and qwen-3-32b with no credit card required. For massive single-request payloads such as full-repository static analysis, Google AI Studio leads with a 1,000,000-token context window and 250,000 to 1,000,000 TPM on gemini-2.5-flash.

Why did GitHub Models (models.inference.ai.azure.com) stop working?

GitHub officially retired the free models.inference.ai.azure.com endpoint on July 30, 2026, transitioning users to paid Microsoft Foundry (models.github.ai) billing tiers. Developers relying on GITHUB_TOKEN for free inference should switch their base URL to Google AI Studio, Groq, Cerebras, or OpenRouter.

How do I prevent free LLM endpoints from training on proprietary source code or PII?

Free tiers frequently subsidize compute by logging prompts for model evaluation (notably Google AI Studio outside the EEA/UK/Switzerland, Mistral's default Experiment tier until opted out in Workspace Privacy settings, and several upstream providers in OpenRouter's :free pool). Never send customer PII, credentials, or proprietary algorithms to public training-enabled free tiers; instead, route sensitive workloads to Cloudflare Workers AI, zero-retention accounts, or self-hosted Ollama / vLLM / llama.cpp endpoints.