---
title: "Client vs. server: where code runs"
description: "What belongs in the browser or app, and what must stay on a server you control."
url: https://lidvizion.ai/resources/basics/backend-client-vs-server/
site: Lid Vizion
index: https://lidvizion.ai/llms.txt
---

[Basics](https://lidvizion.ai/resources/) Architecture

# Client vs. server: where code runs

What belongs in the browser or app, and what must stay on a server you control.

## The split

Client code runs on the user’s device: the browser or a mobile app. Server code runs on machines you control. Anything in the client can be read and changed by the person using it, so the split is a security decision as much as a performance one.

## Keep on the server

These belong behind a server boundary:

- API keys and credentials for AI models and business systems.
- Permission checks: who may read or change what.
- Calls that cost money or act on someone’s behalf.
- Anything that must be logged or approved.

## Good fits for the client

Rendering, instant feedback, input validation for convenience (repeated on the server), and work that should stay on the device for privacy, such as some on-device vision.

Put it to work

## Build the missing piece

Custom tools and applications for the gaps that matter.

[How we do it](https://lidvizion.ai/services/custom-software/)

Keep reading

## More basics.

[All basics](https://lidvizion.ai/resources/)

- [Edge vs. cloud deployment](https://lidvizion.ai/resources/basics/edge-vs-cloud-deployment/): Where a model should run: next to the camera or sensor, or in a data centre.
- [Multi-tenant architecture](https://lidvizion.ai/resources/basics/multi-tenant-architecture/): Serving many customers from one system without letting their data meet.
- [What is computer vision?](https://lidvizion.ai/resources/basics/what-is-computer-vision/): Software that turns images and video into structured information a system can act on.

Bring the messy version

## One workflow. A better way to run it.

Show us the tools, the handoffs, and the part that keeps slowing your team down.

[Let’s map your workflow](https://lidvizion.ai/contact/) · [Read our approach](https://lidvizion.ai/approach/)