Building a Production-Ready RAG System from Scratch
An in-depth overview of building a production-ready RAG system entirely from scratch, with a strong focus on architecture, security, semantic retrieval, and intelligent memory management.
We explain the engineering decisions behind multi-provider LLM orchestration, document processing pipelines, vector search, and hallucination reduction strategies.
We also highlight the practical challenges, performance optimizations, and lessons learned while developing a scalable and reliable AI-powered retrieval system.
November 30, 2025
10 min read
We recently completed a major milestone in the development of our Retrieval-Augmented Generation (RAG) system — a fully custom implementation built entirely from scratch to deeply understand how modern RAG systems work under the hood.
The goal was never just to connect APIs or assemble existing tools together. Instead, we focused on building a production-grade system with strong foundations in architecture, security, performance, and user experience.
Why Build a RAG System from Scratch?
Although there are many frameworks and ready-made libraries available for RAG development, building the system from the ground up gave us a much deeper understanding of the core mechanics behind these architectures.
Through this process, we gained valuable insights into:
The differences between LLM providers and their APIs
How semantic search and vector retrieval actually work
Token management and long-context memory strategies
Security considerations around API key storage and encryption
The engineering challenges involved in building reliable AI systems for production environments
Rather than relying entirely on abstraction layers, we wanted to understand every component in detail and maintain full control over the architecture.
System Architecture Overview
We designed the system as a collection of tightly integrated components working together through a modular architecture.
The core system includes:
An LLM orchestration layer with multi-provider support
A secure API key management layer
Intelligent memory and context management
A vector database for semantic retrieval
A robust document processing pipeline
A modern user interface built with Streamlit
Tags
#RAG
#LLM
#AI
#Vector Search
#ChromaDB
#Python
#Streamlit
Each component was designed independently while maintaining seamless interoperability across the entire workflow.
Multi-Provider LLM Orchestration
One of the core architectural decisions was implementing a unified orchestration layer capable of supporting multiple LLM providers through a single interface.
The system currently supports providers such as:
Groq
OpenAI
Gemini
DeepSeek
For each provider, we implemented dedicated adapters responsible for handling provider-specific API structures, response formats, and operational differences.
This abstraction layer allows the application to switch providers without changing the core business logic, making the system significantly more flexible and future-proof.
Secure API Key Management
Security was treated as a foundational requirement rather than an afterthought.
To protect sensitive credentials, we implemented encrypted API key storage using Fernet symmetric encryption combined with user-specific key derivation.
This approach ensures:
API keys are never stored in plain text
Each user's credentials are encrypted independently
Unauthorized access risks are significantly reduced
By integrating encryption directly into the architecture, we ensured that credential handling remains secure throughout the entire application lifecycle.
Intelligent Memory Management
Managing conversational context efficiently is one of the most challenging aspects of RAG systems, especially when dealing with token limitations and long-running conversations.
To address this, we developed an intelligent memory management system with several core mechanisms.
1. Token-Aware Context Management
The system continuously tracks token usage in real time to prevent exceeding model context limits.
Instead of waiting for API failures, the application proactively monitors token consumption and adjusts memory usage before reaching hard limits.
2. Automatic Context Summarization
As conversations grow larger, older messages are automatically summarized to preserve critical context while reducing token usage.
This allows the system to maintain long conversational sessions without losing important historical information.
3. Intelligent Context Trimming
We implemented logic that determines:
Which information should be retained
Which information can be summarized or removed
This decision-making process considers both recency and contextual relevance to maximize retrieval quality while minimizing unnecessary token consumption.
Semantic Retrieval with ChromaDB
For semantic search, we used ChromaDB combined with HuggingFace embeddings using:
BAAI/bge-small-en-v1.5
This embedding model provided an excellent balance between:
Retrieval quality
Inference speed
Resource efficiency
We also built a custom retrieval layer to improve flexibility and optimize search behavior across different document types.
Document Processing Pipeline
The document pipeline was designed to handle the entire ingestion lifecycle, from upload to semantic indexing.
Multi-Format Document Support
The system supports multiple document formats, including:
PDF
TXT
DOCX
Markdown
Each format uses a dedicated parser optimized for stable and accurate text extraction.
Intelligent Text Chunking
Instead of splitting text arbitrarily, we implemented a semantic chunking strategy that preserves contextual meaning.
The chunking pipeline considers:
Chunk size
Context overlap between chunks
Semantic continuity of text segments
This had a direct impact on retrieval quality and answer accuracy.
Metadata Enrichment
Each stored chunk is enriched with metadata to improve filtering, traceability, and retrieval precision.
Metadata includes:
Source document information
Chunk indexing
Processing timestamps
Total chunk count
This additional context significantly improves search capabilities and debugging workflows.
Reducing Hallucinations
One of the primary goals of the system was minimizing hallucinations and ensuring grounded responses.
To achieve this, we implemented strict system prompting rules that force the model to:
Answer only using retrieved document content
Explicitly state when information is unavailable
Cite document sources clearly
Avoid unsupported assumptions or fabricated information
This dramatically improved response reliability and factual consistency.
Modern User Interface with Streamlit
We built the frontend using Streamlit, with a strong emphasis on usability and user experience.
Key Features
In-app API key configuration
Drag-and-drop document uploads
One-click database and conversation reset
Message copy functionality
PDF conversation export
Real-time processing indicators and feedback
The objective was to make the system accessible even to non-technical users while maintaining advanced functionality.
Performance Optimizations
Several optimizations were implemented to improve responsiveness and reduce operational overhead:
Caching: Reusing embeddings and repeated responses
Batch Processing: Efficient handling of large document uploads
Lazy Loading: Loading components only when required
Connection Pooling: Reusing provider API connections
These optimizations significantly improved both latency and scalability.
Lessons Learned
Building the system from scratch revealed several important engineering insights:
LLM providers differ substantially in behavior and API design
Token management is critical for both stability and cost efficiency
Retrieval quality heavily depends on chunking strategy and embedding selection
Security must be integrated into the architecture from the beginning
User experience is just as important as model quality in AI applications
Future Enhancements
There are several planned improvements for future iterations of the system:
Support for additional document formats such as HTML and JSON
Advanced metadata filtering capabilities
Multi-language retrieval support
Hybrid retrieval combining semantic and keyword search
Query rewriting for improved retrieval quality
Conversation branching and threaded interactions
Analytics and monitoring dashboards
Conclusion
Building a RAG system from scratch was both technically challenging and extremely rewarding. It forced us to deeply understand every layer of the stack — from LLM orchestration and vector databases to security architecture and UX design.
The final result is a production-ready system that includes:
Multi-provider LLM support
Secure API key management
Intelligent memory handling
High-quality semantic retrieval
Robust document processing
A modern and intuitive user interface
Ultimately, the most important takeaway from this project was that building systems from scratch is not about reinventing the wheel — it is about understanding the wheel deeply enough to build better systems on top of it.chitecture, security, performance, and user experience.
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