Browser extension vs firewall for blocking AI tools: which suits a small firm?
For blocking AI tools, a browser extension beats a firewall when staff need to keep using approved AI safely, and a firewall beats an extension when you simply want a site gone. DNS and firewall blocking is all or nothing. Browser controls can check what is pasted or uploaded. An agent on each PC adds coverage at home and stops the extension being removed. Most small firms end up using two of the three.
A note on bias. We make Helio Guard, which uses an agent plus a browser extension. So this comparison leans one way. We have tried to say plainly where the other approaches are the better pick.
The three approaches
DNS and firewall blocking
DNS filtering stops a computer finding a website by name. A firewall stops traffic to it. Either way, the site does not load. Office routers, firewalls and DNS filtering services can all do this.
It is cheap and quick. One rule covers every device on the office network. But it sees only the address, not what is typed. So the choice is block or allow. Nothing in between.
Browser-level controls
Here, a browser extension or a managed browser policy sits inside Chrome or Edge. It can see the page. So it can check a paste, a sent message or a file upload before it leaves. It can take out a card number and let the rest of the question go through.
The weak point is the browser itself. An extension only covers the browsers it is installed in. And if staff can remove it, some will.
Endpoint agents
An endpoint agent is a small program installed on each PC. It runs whatever network the PC is on. Some agents filter web traffic. Others, like ours, install and protect a browser extension so it cannot simply be switched off.
Agents need deploying to every machine. That is a job for whoever looks after your IT. Once in place, they follow the laptop home.
Browser extension vs firewall: side by side
| DNS or firewall | Browser extension alone | Agent plus extension | |
|---|---|---|---|
| Blocks unapproved AI sites | Yes | Yes, in covered browsers | Yes, in covered browsers |
| Lets approved AI through but checks content | No | Yes | Yes |
| Works at home | Only with a VPN or cloud filter | Yes | Yes |
| Covers desktop AI apps | Yes, by address | No | Depends on the product |
| Hard for staff to remove | Yes, on office network | Only if centrally managed | Yes |
| Staff experience | Site will not load | Warnings or items taken out | Warnings or items taken out |
Coverage: what each one actually sees
A firewall sees addresses. That makes it good at one thing: keeping a tool off the network entirely. If you have decided nobody uses DeepSeek, say, a block rule does that well. Our piece on whether to block DeepSeek at work covers that decision.
The catch is new tools. AI sites appear constantly. A block list is always slightly behind. Some DNS services keep category lists, which helps, but none is complete.
A browser extension sees content. It knows the difference between "summarise this letter" and a pasted client list. It cannot see a desktop app or a phone.
Neither sees personal phones on mobile data. No technical control does. That gap is covered by policy and training, not software.
Home working changes the answer
Office firewall rules stop at the office door. A laptop on home broadband ignores them. To extend them you need an always-on VPN or a cloud DNS filter set on each device.
Browser controls and agents travel with the PC. Tom at Ashcombe works Fridays from home. With an extension, his pastes into ChatGPT are checked the same as on Monday.
Rule of thumb: if more than a few staff work from home, any control that lives only on the office network is a part-time control.
Staff experience and approved AI
This is where the approaches differ most. A block stops the work. Priya needs to tidy a client letter. The site will not load. She tries her phone instead. Now nothing is checked at all.
Content checking keeps the tool open. Priya pastes the letter. The client's bank details are taken out and replaced with a label. The question still goes. She gets her answer.
That matters because most firms want AI used, just safely. Blocking everything rarely matches the policy. It mostly pushes use somewhere you cannot see. If you are not sure what is in use now, start by working out which AI tools your staff are using.
Which approach suits your setup
- Everyone in the office, a short list of banned tools: firewall or DNS blocking is enough to start.
- Approved AI in daily use with client data: you need content checks in the browser. A block cannot tell good use from bad.
- Hybrid or remote staff: use a cloud DNS filter or an agent so rules follow the laptop.
- Staff with admin rights on their PCs: an unmanaged extension will not last. Use central browser policy or an agent.
- Macs in the mix: check each product's platform list carefully before choosing.
A sensible pairing for many small firms: DNS blocking for tools you never allow, plus browser checks on the ones you do.
Where Helio Guard falls short
Helio Guard is an agent plus an extension. It works on Windows PCs, in Chrome and Edge, on listed AI sites. It does not cover Macs, phones, other browsers or desktop AI apps. A firewall rule still does a better job of blocking a tool outright on the office network.
What it does do: checks each paste, message and file upload on the PC with fixed rules, not an AI model. Sensitive items are taken out, warned about, stopped or recorded. Client names can become a stand-in such as "Client A". We never see what your team types. It also flags unapproved AI tools. You can see how it stacks up against other tools on our comparison page, and it is £1 a person a month, from 5 people, as listed on our pricing page.
Common questions about blocking AI tools
Can staff get around a browser extension that blocks AI?
Staff can get around a browser extension if they can remove it or use another browser. Managed browser policies and endpoint agents stop removal. Blocking unsupported browsers closes the second gap. Without either, an extension is a guide rather than a control, which suits some firms but not those handling sensitive client data.
Is DNS blocking enough to stop ChatGPT at work?
DNS blocking stops ChatGPT loading on devices using your filtered DNS. It does not cover home broadband unless the filter is set on each device, and it cannot allow safe use while stopping risky pastes. For firms that want ChatGPT used carefully, DNS blocking alone is usually too blunt.
Do I need both a firewall and a browser extension for AI?
Many small firms benefit from both a firewall and a browser extension for AI control. The firewall or DNS filter keeps banned tools off entirely. The extension checks what goes into approved tools. Each covers a gap the other leaves, and together they match a policy that welcomes AI but keeps client data out.
Related: ChatGPT Team vs Enterprise security controls: a control-by-control checklist