Offline-first design: a practical guide

It is rarely the thing that gets a project approved, and often the thing that decides how it goes. This guide covers what offline-first design actually involves, where it usually goes wrong, and how to tell whether yours is in reasonable shape.

You do not control the device, the network, or the operating system version, and the design has to accept that. Nothing below assumes a large team or a large budget — most of it is a decision somebody has to make and then write down.

The reason this keeps coming up

Connections drop, and the app should keep working. The cost of getting this wrong is rarely visible on the day it happens. Check it against what you would want a competitor's site to get wrong.

For most businesses the question is not whether this matters but how much of it is worth doing right now. That depends on what you are trying to achieve in the next few months, not on best practice in the abstract. Getting it slightly wrong is survivable. Ignoring it entirely is not.

How to approach it

Conflict resolution is the part teams forget to design. The teams that handle this well are rarely the ones with the biggest budgets. Anything you cannot measure here, you are deciding by taste, which is fine as long as everyone knows it.

Mobile releases are slower to correct than web ones, so the cost of shipping a mistake is higher. The version that works in practice is usually less elaborate than the version described in the guides.

Show sync state so people trust what they see. This is the sort of thing that compounds, quietly, in both directions. Most teams find the first pass takes an afternoon and the maintenance takes minutes a month.

A working checklist

If you want a quick read on where you stand, work through this. Anything you cannot answer confidently is where to start.

• Connections drop, and the app should keep working
• Conflict resolution is the part teams forget to design
• Show sync state so people trust what they see
• Someone is named as the owner, not just assumed to be
• There is a date in the calendar to review it again
• The decision and the reasoning behind it are written down somewhere findable
• You could explain the current setup to a new hire in five minutes

Where it usually goes wrong

The most common failure is not doing this badly. It is doing it once, during a launch, and never revisiting it. Circumstances move, the setup does not, and the gap widens quietly until something breaks or somebody notices the numbers.

• It was configured during a launch and has not been touched since
• Different people in the business believe different things are true about it
• There is no way to tell whether the last change helped or hurt
• The only person who understands it has left, or is about to

The version of the app your customers are running is rarely the one you just shipped. Getting it slightly wrong is survivable. Ignoring it entirely is not.

How we approach it

On our projects this gets handled during the build rather than added afterwards, because retrofitting it costs several times more than including it. We write down what was decided and why, so the next person to touch it is not guessing.

If you are working with someone else, the questions worth asking are simple: who owns this, how will we know it is working, and what happens when it needs to change?

What to do next

Pick the single item from the checklist above that would cause the most trouble if it turned out to be wrong. Fix that one, confirm it worked, then move on. If any of that sounds like a description of your current setup, it is fixable.