Under the Hood: The Tech Stack Behind ReplyFox
July 26, 2025
At first glance, ReplyFox is simple: it replies to Instagram comments so you don’t have to. But under the hood, there’s quite a bit going on.
We thought it would be fun to share what powers ReplyFox — the stack, the AI, and the behind-the-scenes magic that makes it all work.
Spoiler: it’s not a bunch of predefined templates. It’s smarter than that.
A Pythonic Backbone with FastAPI
Let’s start with the basics: the app is built with FastAPI, a modern Python framework that’s fast, clean, and async-friendly. It helps us keep things snappy and flexible as we scale.
FastAPI handles the backend logic, Instagram connection, and the comment processing pipeline — all behind a clean, simple dashboard.
Official Instagram Integration via Meta’s API
ReplyFox connects directly to Instagram Business Accounts using the Meta Graph API. That means real-time access to comments, seamless replies, and full compliance with Meta’s ecosystem.
We’re also a Facebook-verified business and run a properly configured Meta App with the necessary OAuth permissions. So when you connect your account, you’re not just safe — you’re fully supported by the platform.
Redis + PostgreSQL: Fast and Reliable
We use Redis to manage in-memory queues and ensure comments are processed in the right order, especially during traffic spikes.
All the core data — user profiles, reply logs, preferences — lives in PostgreSQL, giving us a stable, structured foundation with plenty of room to grow.
Smart Replies with OpenAI
The heart of ReplyFox is our reply engine, powered by OpenAI.
Whenever a new comment comes in, we craft a prompt that includes your business context and pass it to GPT to generate a smart, relevant reply. No canned templates, no random guesses — just helpful, human-sounding responses.
Context-Aware Replies Using Qdrant
To make those replies better, we add context using Qdrant, our vector database.
We store all your business information — what you do, how you speak, your FAQs, previous Q&A — and when a new comment arrives, we search this context using embeddings. The result: the AI knows what matters and responds accordingly.
It’s what makes ReplyFox feel personal, even though it’s automated.
Seamless Payments with Stripe
All payments and subscriptions are handled through Stripe — a secure, trusted platform used by millions of businesses around the world. You can manage your plan, view invoices, and upgrade or cancel anytime through your Stripe-powered billing portal.
That’s the Stack
So yes — ReplyFox may look simple on the surface, but under the hood, it’s powered by real-time APIs, AI models, vector search, and rock-solid infrastructure.
We built it to save you time, help you engage better, and actually sound like a real human in the comments.
If you haven’t tried it yet, connect your Instagram Business page and let ReplyFox do the heavy lifting.