Llm

Google’s Gemma 4 is not one model - it is a family of four, each targeting different hardware and different use cases. The smallest runs on a Raspberry Pi. The largest ranks #3 on LMArena across all models, open and closed. All four ship under the Apache 2.0 license, a first for the Gemma family. This guide walks through installing each variant with Ollama (currently at v0.20.2), benchmarks them on real consumer hardware, and helps you decide which one fits your setup.

Google’s Gemma 4 family covers the 2.3B E2B, 4.5B E4B, 26B MoE, and 31B dense variants. It delivers strong open-weight performance across text, vision, and audio. But general-purpose models still struggle with narrow tasks. You often need a fixed output format, special terms, or facts that weren’t in the training data. Fine-tuning fixes this. Unsloth makes it work on a single consumer GPU. Its custom CUDA kernels cut VRAM by up to 60% and double training speed next to a standard Hugging Face plus PEFT setup.

For most developers in 2026, Gemma 4 31B is the best all-around open model. It ranks #3 on the LMArena leaderboard, scores 85.2% on MMLU Pro, and ships under Apache 2.0 with zero usage limits. Qwen 3.5 27B edges it on coding, and its Omni variant offers real-time speech output that no other open model matches. Llama 4 Maverick (400B MoE) wins on raw scale, but it needs datacenter hardware and Meta’s restrictive 700M MAU license. So pick Gemma 4 for the best quality-to-size ratio, Qwen 3.5 for coding-heavy work, and Llama 4 only when you need the largest open model.

You can unify access to Ollama, vLLM, cloud providers like OpenAI, Anthropic, and Google, plus custom model servers behind one OpenAI-compatible endpoint using LiteLLM Proxy . LiteLLM is a reverse proxy. It maps the standard /v1/chat/completions request to each provider’s native API. From one YAML file it handles auth, model routing, load balancing, fallbacks, rate limits, and spend tracking. Your app calls one endpoint with one key, and LiteLLM picks the right backend. You can swap models, add providers, or run A/B tests without touching app code.

Agentic RAG replaces the standard “retrieve-then-generate” pattern. The LLM gets tool-use powers to decide when to retrieve, which sources to query, how to rewrite queries, and whether the result is enough. Instead of fetching docs on every query, the model acts as an orchestrator. It runs targeted searches across vector stores, SQL databases, and web sources, then checks its own answers. This pattern lifts answer accuracy by 15-25% on multi-hop benchmarks and cuts wasted retrieval calls by about 35%.

You can harden LLM apps against prompt injection and data leaks by stacking defenses. Input cleanup strips control tokens before they hit the model. Output filters scan replies for PII and secrets. Structured output forces the model to follow a fixed schema. Add a system prompt firewall that walls off trusted rules from user input. Together they turn one bare API call into a pipeline. Bad prompts get caught before the model runs. Risky data gets redacted after. No single layer is bulletproof. Stacked, they cut the attack surface enough that most threats give up.