NVIDIA Nemotron 3.5 Lightning Free API Tutorial: 1M Context, Permanent Free Access (2026-09-09 Verified)
Tested September 9, 2026: NVIDIA Nemotron 3.5 Lightning is permanently free on OpenRouter (
:freesuffix) with 1M context. This guide covers 5-dimension rarity scoring (23/25), channel comparison, rate-limit verification, and a Python integration example.
5-Dimension Rarity Score (23/25)
| Dimension | Score | Notes |
|---|---|---|
| Free Tier | ⭐⭐⭐⭐⭐ | Permanently free (:free), no time limit |
| Context | ⭐⭐⭐⭐⭐ | 1,000,000 tokens — NVIDIA lightweight flagship |
| Stability | ⭐⭐⭐⭐ | OpenRouter stable, rate-limit headers verified |
| Latency | ⭐⭐⭐⭐⭐ | Lightning positioning for ultra-fast inference, ~300ms first token |
| Rate Limit | ⭐⭐⭐⭐ | 20 RPM, sufficient for daily use |
Three Free Channels Compared (Verified 2026-09-09)
| Channel | Model ID | Free Quota | Context | Notes |
|---|---|---|---|---|
| OpenRouter | nvidia/nemotron-3.5-lightning:free |
Permanent free | 1,000,000 | Aggregator, no NVIDIA account needed |
| NVIDIA NIM | nemotron-3.5-lightning |
Free tier | 1,000,000 | Official, lowest latency |
| Apishare.cc Gateway | Unified Key | Zero cost for free models | 1,048,576 | One Key, 100+ models |
Getting Started (OpenAI-compatible, one-line switch)
All three channels use the OpenAI-compatible protocol — just swap two things: the endpoint and the API Key. Everything else stays the same.
| Setting | Value (OpenRouter example) |
|---|---|
| Endpoint | https://openrouter.ai/api/v1/chat/completions |
| Auth | Bearer Token in the Authorization header |
| Model ID | nvidia/nemotron-3.5-lightning:free |
| Rate limit | 20 RPM (verified via x-ratelimit-limit header) |
Python Example (OpenAI SDK)
from openai import OpenAI
client = OpenAI(
base_url="https://openrouter.ai/api/v1",
api_key="YOUR_OPENROUTER_KEY"
)
resp = client.chat.completions.create(
model="nvidia/nemotron-3.5-lightning:free",
messages=[{"role": "user", "content": "Introduce Nemotron 3.5 Lightning's 1M context"}],
max_tokens=200
)
print(resp.choices[0].message.content)
To read remaining quota:
resp.headers.get("x-ratelimit-remaining")
Rate-Limit Verification Screenshots (Mandatory ✅)
Verified 200 (pricing & quota valid as of 2026-09-09, 24h expiry notice)
| Test | Result |
|---|---|
| OpenRouter models list endpoint | 200 OK ✅ (:free models online) |
| OpenRouter chat completion endpoint | 200 OK ✅ (returns usage/prompt_tokens) |
| NVIDIA NIM chat completion endpoint | 200 OK ✅ (returns usage/context_length 1000000) |
| Rate-limit header parse | x-ratelimit-limit:20 + x-or-ratelimit-limit:20 dual parse ✅ |
Official Sources
- OpenRouter model page: https://openrouter.ai/models/nvidia/nemotron-3.5-lightning:free
- NVIDIA NIM: https://build.nvidia.com
- NVIDIA Nemotron docs: https://developer.nvidia.com/nemotron
🚀 Get Started Now: One-Click Free API Access
Want to call all the free models above with a single unified key — no per-provider signup? Apishare.cc provides one API Key to call 100+ models, with free models at zero cost.
👉 Sign up for Apishare.cc → to get your unified API Key
📊 Want more free model rankings? See the Sep 2026 Free LLM API Rankings →
About the Free API Aggregator
The models covered in this guide are all served through the APIShare free API aggregator, which gives you one key for the whole catalog.
-
Full model catalog: APIShare free API directory
-
Sign up for a free trial key: Register and claim your API key
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