Guide
What "offline" means, technically
Every field-forms vendor writes "works offline". The word covers at least three very different realities, and the difference is paid the day a crew spends a day in a dead zone.
15 days • 10 users • no card required
The three levels
From read-only to full autonomy
Knowing which of the three you are buying is the only question that matters, and it fits in one sentence: "in airplane mode, what can I do with a form I have never opened?"
- Level 1 — viewing
- The last screen loaded stays on display. Nothing more: opening another form fails. That is a browser cache, not an offline app.
- Level 2 — simple entry
- You can fill in, but reference lists, calculations or attachments need the network. The form works as long as it stays simple.
- Level 3 — autonomy
- The form, its rules, its calculations and its lists live on the device. The network only exchanges. It is the only level that survives a day on site.
Where it breaks
The four places it goes wrong
An offline product is not judged when everything works: it is judged on these four situations, all of which happen in real operation.
- The drop mid-upload
- Without resume, a four-megabyte photo restarts from zero on every attempt, and on an unstable network it never leaves.
- The same record changed on both sides
- Two options: overwrite quietly, or show the conflict and ask. The first is comfortable for the vendor and expensive for the customer.
- The queue that empties itself
- Some apps purge after a delay or after an update. Ask explicitly what triggers a deletion.
- The form republished mid-entry
- If the submission is not attached to a frozen version, it changes shape along the way, and nobody knows what was signed.
Before signing
Five questions to ask any vendor
Including us. The answers can be checked in ten minutes with a phone in airplane mode.
- "What happens if I have no network for three days?"
- The answer must contain an explicit limit, or the absence of one. "It should be fine" is not an answer.
- "What can delete a pending submission?"
- The list should be short and contain only user actions.
- "What does the technician see when an upload fails?"
- A visible state, or nothing. The second answer means the office will call the field to find out.
Can a web app work offline?
Partly, with a service worker and local storage. The limits show up on storage size, sensor access and how long data survives when the browser reclaims space. For a full day of entry with photos, an installed app remains safer.
Should syncing be manual?
No, and it is a bad sign when it has to be: manual syncing moves the responsibility for not losing data onto the technician.
Test the answer rather than believe it
Airplane mode, a full form, photos, signature, then the network back. Ten minutes is enough to separate two products.