We’ve all spent the last few years talking a lot about AI, and rightly so. The cloud gives us scale, the latest frontier models, and a constant stream of new capabilities. But somewhere along the way, “AI” became shorthand for “send it to the cloud,” and I think that’s worth talking about. Not because the cloud is wrong, but because it isn’t always the right answer. Sometimes you’re on a train with no signal. Sometimes the data simply isn’t allowed to leave the device. And sometimes you just don’t want to spend tokens on a task your laptop can quietly handle on its own.
These points led me to try building something I can try out for real and then talk about with my colleagues and our customers.
If you’ve invested in Copilot+ PCs, you have already paid for a surprising amount of on-device compute, and increasingly, newer devices ship with even more. So why let it sit idle? In this blog post, I want to show that local AI genuinely works, share two demo agents I built that run entirely offline, and give you a basic comparison of what you gain (and what you trade) when you keep a workload on the device instead of sending it to the cloud.
We will cover the following topics:
When I started experimenting with on-device agents, I wasn’t trying to replace cloud AI, I was trying to fill some gaps and have real-life examples I can show to my colleagues and our customers, no smoke and mirrors. Three real-world scenarios came up frequently:
The interesting bit is that you don’t have to choose one world over the other, you can mix and match. Run the routine, sensitive or offline work locally, and reach for the cloud when you genuinely need its power.
Local AI devices: Before we get to the demos, it’s worth noting we have several choices when it comes to devices we can run local AI on and the choices are growing even in compute and governance. For the demos below, they were run against Microsoft Surface and Dell devices using a mix of silicon such as Intel and Qualcomm.
The first agent solves a problem we all recognise: the chaos of an unmanaged Downloads folder. Auto Filer is a local agent that watches a location you choose, understands what each new document is, and files it away into a folder structure you define, all on the device with no cloud round-trip.
Here’s how it works in practice:
The clever part is that the model reads and reasons about the content locally to make the filing decision. For example, an invoice goes to your finance folder, a signed contract to the right client subfolder, a draft proposal into the active opportunities tree, without you dragging a single file, and without any of those documents being sent anywhere.
Bonus tip: Because the triage source and the destination are both things you define, Auto Filer adapts to how you already work rather than forcing a new system on you. Point it at OneDrive as the destination and you get the best of both worlds: local, private classification with cloud-backed durability.
The second agent is a natural follow up from the first agent (in my mind anyway). Confidential Knowledge Agent is a local, vector-based chat agent that looks and feels like the online AI chat experiences we have all become used to, except it runs entirely on the device against a local vector database.
A few things make it genuinely useful rather than just a novelty:
For confidential or regulated knowledge, the content is indexed and queried locally, the answers never leave the device, and you still get a transparent confidence signal to guide when escalation to the cloud makes sense.
If you're not using Microsoft Copilot (why not) then a common cloud baseline is Azure AI Search (for the vector index) plus something like Azure OpenAI GPT-5.4 (for generation) and text-embeddings. Assuming a knowledge worker running 20 retrieval-augmented queries per day over a 500 MB personal & shared corpus re-indexed monthly, we might see the following per-user annual profile.
|
Component |
Assumption |
Cloud cost (£/user/yr) |
|
Embedding index (re-index monthly) |
125M tokens × 12 × $0.13/1M |
≈ £154 |
|
Query embeddings |
~0.15 M tokens/year, $0.02/1M |
negligible |
|
GPT-5.4 generation |
~5,000 queries × (4k in + 600 out) |
≈ £75 |
|
Azure AI Search standard tier (shared) |
S2 service, ~2 SUs ÷ 1,000 users |
≈ £19 |
|
Egress and ancillary Azure |
Occasional corpus sync |
≈ £10 |
|
Total cloud baseline |
|
≈ £258 |
|
Local implementation |
Hardware already capex |
≈ £0 |
|
Spend per user per year |
|
≈ £258 |
All figures are pay-as-you-go list prices (UK region, GBP) at time of writing this blog post with no reserved-capacity or volume discounts applied, directly reflecting the latest official Azure pricing sources.
At a thousand users, this is roughly £258,000 per year of cloud spend for a single workload.
Some more comparisons to consider:
|
|
Auto Filer - Cloud |
Auto Filer - Local |
Confidential Knowledge Agent - Cloud |
Confidential Knowledge Agent - Local |
|
Connectivity required |
Yes - needs a live connection to classify and file |
No - works fully offline |
Yes - every query needs the cloud |
No - answers offline from the local vector DB |
|
Data residency |
Document contents leave the device |
Contents never leave the device |
Query + context sent to the cloud |
Query + knowledge stay on the device |
|
Token / running cost |
Per-document token spend |
No token cost - uses on-device compute |
Per-query token spend |
No token cost per query |
|
Latency |
Network round-trip per file |
Fast, local |
Network round-trip per question |
Fast, local retrieval |
|
Model power |
Highest - frontier models |
Right-sized small model, ample for the task |
Highest - best reasoning |
Good for known-base Q&A; escalate when needed |
|
Best suited to |
Complex, ambiguous documents |
High-volume, routine, sensitive filing |
Open-ended, novel questions |
Confidential, offline, repeatable queries |
The local option does well on privacy, cost and resilience, while the cloud wins on raw model power for the genuinely hard, open-ended problems. Neither is “better”, they’re complementary. With each new generation of Copilot+ PCs shipping more on-device compute, the range of tasks that run comfortably and quickly on the local side keeps growing.
For the devs: Using Foundry local wasn’t difficult and we have choices of what optimised model to use. I tried Phi and Qwen across multiple devices for example and as a dev, you have other choices of models and various ways to deploy these tools to your end user devices.
In this blog post we challenged the assumption that AI has to mean cloud AI. Local agents running on Copilot+ PCs are a real, practical option and not a compromise. We looked at two demo agents, Auto Filer for local document triage and filing, and the Confidential Knowledge Agent for offline, confidence-aware chat over a private knowledge base, and we compared how each performs locally versus in the cloud.
Some key takeaways:
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