Engineering
How we rebuilt sync for crews that work without signal
Hana Kowalski · Oct 28, 2026 · 7 min read
Most of our customers spend their day in basements, wind farms and hospital wards. Signal comes and goes, and the old sync engine treated every drop as an error. Field crews were losing photos, and supervisors were re-entering checklists by hand at the end of a shift.
We started from one rule: the device is the source of truth until the server says otherwise. Every edit is written locally first, stamped with a logical clock and replayed in order once a connection returns.
Conflicts are a product problem
Two inspectors editing the same checklist is not rare, it is Tuesday. Instead of silently picking a winner, the new engine merges field by field and shows a small diff when two people changed the same answer.
The result after six weeks in beta: sync failures down 92 percent, median upload time from 14 seconds to 1.8, and zero lost photos across 410,000 inspections.
What comes next
Background uploads on Android, selective sync for very large sites, and an audit trail that shows exactly when each change reached the server.
Social proof · 12View all
Loved by teams everywhere
Thousands of teams rely on us every day. Here is what a few of them have to say.
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Case studies
Teams that switched, and the numbers that followed
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0.0x
faster dispatch planning
0%
fewer support tickets
$0.0M
added annual revenue
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Teams ship faster the week they switch
Twelve thousand engineering teams run production on Vantage. Here is what a few of them told us, unedited.
We moved 40 services over in a weekend. The migration guide was better than our own docs.
Rollbacks take one click. I stopped dreading Friday deploys.
New hires ship to production on day one. That used to take three weeks.
We moved 40 services over in a weekend. The migration guide was better than our own docs.
Rollbacks take one click. I stopped dreading Friday deploys.
New hires ship to production on day one. That used to take three weeks.
Preview links on every pull request changed how design reviews happen here.
Support answered a routing question at 2am with a working config attached.
Edge caching alone paid for the whole plan in the first month.
Preview links on every pull request changed how design reviews happen here.
Support answered a routing question at 2am with a working config attached.
Edge caching alone paid for the whole plan in the first month.
Our p95 dropped from 840ms to 190ms without touching application code.
Logs, traces and deploys in one timeline. Incidents read like a story now.
It feels like the platform team we could never afford to hire.
Our p95 dropped from 840ms to 190ms without touching application code.
Logs, traces and deploys in one timeline. Incidents read like a story now.
It feels like the platform team we could never afford to hire.
The bill went down and the on-call rotation got quiet. Rare combination.
We cut our infrastructure repo from 12,000 lines to about 300.
Branch databases made our test suite honest for the first time.
The bill went down and the on-call rotation got quiet. Rare combination.
We cut our infrastructure repo from 12,000 lines to about 300.
Branch databases made our test suite honest for the first time.
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Heard from teams on Ledgerly
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The companies you use every day ship with Relay
Clinics in six countries rely on us at 3am local time. The platform has never been the reason they waited.
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We were doing every order on paper.
We were doing every order on paper. Now the shop runs on Tillwise from one tablet. Saturday mornings went from chaos to calm. And I finally take Sundays off.
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I edit on flights and it merges perfectly the moment I land.
Embedded checklists made new hire setup take a day instead of a week.
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Loved by teams who ship every week
Over 3,800 engineering teams run their releases on Lumen. Here is what a few of them had to say.
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Customer results
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Measured by the teams themselves, twelve months after switching to Relay.
3.2x3.2x
faster deploys to production
−41%−41%
churn in the first 90 days
$1.8M$1.8M
saved on infrastructure in year one
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