Llama 3.1 405B — Meta | Modeldex

Llama 3.1 405B

Active

Meta's largest open-weights model, competitive with frontier closed models.

Updated 4 days agoStructured data from Modeldex catalog

AgenticOpen sourceCode

Not enough benchmark coverage yet for an Intelligence Index — needs at least 3 results across 2 categories.

Overview

Llama 3.1 405B is Meta's 405-billion-parameter open-weights model with 128k context. It represents the state of the art for openly available models and requires multi-GPU or distributed inference.

History

Llama 3.1 405B was released on 2024-07-23.

Training & availability

Weights are publicly available under the Llama 3.1 Community License license, making this an open-weight model suitable for on-prem deployment and fine-tuning.

Capabilities

Context window: 128K tokens.
Max output: 8K tokens.
Input modalities: text.

Recommended for: agentic, open-source, code.

Limitations

Text-only — cannot process images, audio, or video inputs.

Quick start

Minimal example using the OpenRouter API. Copy, paste, replace the key.

from openai import OpenAI

client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key="sk-or-...",
)
resp = client.chat.completions.create(
    model="meta/llama-3-1-405b",
    messages=[{"role": "user", "content": "Explain quantum computing in one sentence."}],
)
print(resp.choices[0].message.content)

Benchmarks

Benchmark	Score	Source
HumanEvalCoding	89pass@1 %	Self-reported Meta system card

Integrations & tooling support

Tool calling: Supported
Structured outputs: Not supported

Price vs quality

Below-average benchmarks

Performance trails frontier models. Pricing not publicly available — check the provider.