Chat is the norm now. When you build a marketplace, a healthcare app or a SaaS dashboard, people expect to message someone without leaving the app and when that feature is missing, they know it.
The shift has now put product teams into an old dilemma and raised a question of which is better: “Building a chat app infrastructure from scratch or buying an existing chat API”.
This post describes what it takes to build an in-house chat, the time and money it involves, what security work gets skipped and how it compares to buying a prebuilt chat solution.
What Building Chat In-House Actually Involves?
You must understand the scope before you can estimate the cost. It isn't just about writing a messaging UI, but building a real-time chat system underneath it as well.
Real-Time Infrastructure
Chat needs persistent bidirectional connections instead of the request-response pattern of a normal web app. That means putting up WebSocket servers that can hold thousands or millions of open connections at once.
If your user base is growing too, you also need connection routing logic to find a user's active session among potentially many servers, a real hard distributed systems problem.
Data Storage
Every message needs a place to live along with media files, read states and presence history. This involves defining a database schema that stores both structured data such as user permissions and less structured data such as message threads and metadata at once.
Client-Side State Management
They're expecting the same chat history on a phone, laptop or tablet. Real-time state synchronization across devices without duplicate messages and missed updates takes some care on the client side, especially when a device goes offline mid-conversation but reconnects later on.
The Feature Checklist Users Expect
Even with all that infrastructure in place, people still expect some sort of baseline feature set once the app is "done":
- Reading receipts
- Delivery confirmations
- Typing indicators
- Online/offline presence status
- Media and File sharing
- Push notifications on iOS and Android
These seem relatively easy to build on their own, but when combining all these, the actual execution for instant messaging app development takes longer than expected.
Time and Team Cost to Build This In-House
Here the numbers get real. To build a basic chat MVP including messaging, presence and simple notifications, it takes 3 to 6 months for a team of 3 to 5 engineers. That's the minimum for building a working prototype that is not ready for handling thousands of concurrent users.
With a similarly sized team, it takes 10 to 15 months to build a production version with encryption, multi-device sync, scalable infrastructure and proper testing across edge cases.
Those who have built chat from scratch at an enterprise scale estimate it to be worth millions, including infrastructure, maintenance and engineering hours needed to keep it running.
The gap between an MVP and a production-ready chat system is where teams underestimate the cost and time the most.
Security: What Gets Overlooked When Building In-House
This is the part that most teams never really think through very carefully until something goes wrong.
Encryption in Transit & at Rest
Messages need to be encrypted both in transit and in your database. When you bypass transit encryption, you allow conversations to be intercepted on unprotected networks.
If you leave encryption at rest, a database breach is enough to leak every conversation your users ever had.
Token Handling & Authentication for Real Time Connections
Since WebSocket connections stay open much longer than an HTTP request, real-time connections require their own authentication logic outside of your standard login flow.
If token expiration and refresh are not handled well, you kick users out mid-conversation or worse, you leave stale sessions open for hijack.
Compliance Requirements
When it comes to health & financial data, HIPAA & GDPR are mandatory. Here, failing to implement data residency controls or audit logging can cost you a fine or even lose enterprise clients. Altogether during a security review compliance issues are often the deciding factors in procurement.
Ongoing Maintenance Nobody Budgets For
Launching your chat feature is only the beginning. As your user base grows, server costs scale with concurrent connections, not just total signups.
A basic setup supporting 10,000 concurrent users may by now run several thousand bucks monthly in infrastructure by yourself, and that number climbs fast as use expands.
Plus you have to keep patching security as new vulnerabilities emerge, you have to spend engineering time on bugs that appear under actual traffic.
Also, you have to pay the quiet opportunity cost of having your best engineers spend months on chat infrastructure rather than working on your real product.
What You Get When You Buy a Chat API Instead
Buying a chat API changes everything. No longer do teams need to wait for 6 to 15 months to implement a chat SDK, as it takes only days or weeks on average.
The solution provider takes care of security, scaling and compliance certifications so you do not build and maintain your own team communication app from scratch.
Here’s a Quick Comparison of Building In-House vs Buying a Chat API
| Factor | Build In-House | Buy a Chat API |
|---|---|---|
| Time to launch | 6–15 months | Days to a few weeks |
| Team required | 3–5 dedicated engineers | 1 engineer for integration |
| Upfront cost | High (salaries + infra) | Low (subscription-based) |
| Ongoing cost | Hosting, scaling, maintenance | Predictable monthly pricing |
| Security & compliance | You own it entirely | Handled by vendor (end-to-end encryption, GDPR/HIPAA certificates) |
| Feature scope | Only what you build | Full feature set from day one (read receipts, presence, media, push) |
| Customization | Full control | Limited to what the SDK/API exposes |
| Maintenance | Your team's ongoing responsibility | Vendor handles updates, patches, scaling |
| Best for | Chat is your core product | Chat is a feature in a larger product |
Providers like MirrorFly, GetStream, Sendbird and CometChat all go about it slightly differently.
For those who need data residency and the usual enterprise instant messaging features, MirrorFly offers a self-hosted deployment option.
GetStream and SendBird offer fully managed cloud infrastructure with free tiers for smaller apps. Whereas CometChat provides pre-built UI kits for quick front-end integration.
Considering a chat app strategy without months of infrastructure work? MirrorFly's chat API and SDK are worth a look for teams that want deployment flexibility baked in from day one.
Who Should Build and Who Should Buy a Chat App?
The right choice is less about budget and more about what role chat plays in your product.
| Build If | Buy If |
|---|---|
| Chat is your core product and not a supporting feature. | Chat is a feature of a larger product, not the main offering. |
| You have a dedicated real-time engineering team. | Your team cannot afford to spend months on infrastructure work. |
| You have strict compliance or data residency requirements that off-the-shelf SDKs can't meet. | All major chat API providers already cover your compliance needs. |
Final Verdict
How much it costs to build a chat app depends entirely on how central chat is to your product. But building it in-house means total freedom of design and customization, but it takes real engineering, with 6 to 15 months of time and a dedicated team that never stops.
When you buy the right Chat API, you get the flexibility, speed, ownership and cost that you expect. There's no right answer that fits everyone, just the right chat tool for what your product and team require today.
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