🚀 PromptCache

Reduce your LLM costs. Accelerate your application.

A smart semantic cache for high-scale GenAI workloads.

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💰 The Problem

In production, a large percentage of LLM requests are repetitive:

• RAG applications: Variations of the same employee questions
• AI Agents: Repeated reasoning steps or tool calls
• Support Bots: Thousands of similar customer queries

Every redundant request means extra token cost and extra latency.

Why pay your LLM provider multiple times for the same answer?

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💡 The Solution: PromptCache

PromptCache is a lightweight middleware that sits between your application and your LLM provider. It uses semantic understanding to detect when a new prompt has the same intent as a previous one — and returns the cached result instantly.

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📊 Key Benefits

Metric	Without Cache	With PromptCache	Benefit
Cost per 1,000 Requests	≈ $30	≈ $6	Lower cost
Avg Latency	~1.5s	~300ms	Faster UX
Throughput	API-limited	Unlimited	Better scale

Numbers vary per model, but the pattern holds across real workloads: semantic caching dramatically reduces cost and latency.

* Results may vary depending on model, usage patterns, and configuration.

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🧠 Smart Semantic Matching (Safer by Design)

Naive semantic caches can be risky — they may return incorrect answers when prompts look similar but differ in intent.

PromptCache uses a two-stage verification strategy to ensure accuracy:

1. High similarity → direct cache hit
2. Low similarity → skip cache directly
3. Gray zone → intent check using a small, cheap verification model

This ensures cached responses are semantically correct, not just “close enough”.

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🚀 Quick Start

PromptCache works as a drop-in replacement for the OpenAI API.

1. Run the server

git clone https://github.com/messkan/prompt-cache.git
cd prompt-cache
make run

2. Update your client

Simply change the base_url in your SDK:

from openai import OpenAI

client = OpenAI(
    base_url="http://localhost:8080/v1",  # Point to PromptCache
    api_key="sk-..."
)

# First request → goes to the LLM provider
client.chat.completions.create(
    model="gpt-4",
    messages=[{"role": "user", "content": "Explain quantum physics"}]
)

# Semantically similar request → served from PromptCache
client.chat.completions.create(
    model="gpt-4",
    messages=[{"role": "user", "content": "How does quantum physics work?"}]
)

No code changes. Just point your client to PromptCache.

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🏗 Architecture Overview

Built for speed, safety, and reliability:

• Pure Go implementation (high concurrency, minimal overhead)
• BadgerDB for fast embedded persistent storage
• In-memory caching for ultra-fast responses
• OpenAI-compatible API for seamless integration
• Docker Setup

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🛣️ Roadmap

✔️ v0.1 (In progress - not stable)

• In-memory & BadgerDB storage
• Smart semantic verification (dual-threshold + intent check)
• OpenAI API compatibility

🚧 v0.2

• Redis backend for distributed caching
• Web dashboard (hit rate, latency, cost metrics)
• Built-in support for Claude & Mistral APIs

🚀 v1.0

• Clustered mode (Raft or gossip-based replication)
• Custom embedding backends (Ollama, local models)
• Rate-limiting & request shaping

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📄 License

MIT License.