The phone rings at 7:40 pm.It gets answered.

Gesser OS runs the office side of a service business. A receptionist picks up your line and books the visit. The work order, the estimate and the invoice stay on one page until the money is in.

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Tuesday, 7:40 pm. One call, as it happens.

Your business line is ringing.
Receptionist
Thanks for calling Harbor Home Services. How can I help?
Caller
There's water coming through the kitchen ceiling, right under the upstairs bathroom.Half the kitchen went dead and the breaker won't stay reset.We need the office deep-cleaned before we reopen on Monday.The heat quit overnight and the house is down to 58.We just bought the house and want the whole first floor painted before we move in.The sprinklers on the left side of the yard stopped coming on.
Receptionist
I can put someone on the schedule for tomorrow. I have 9:00 or 1:30.
Caller
Nine works.
Receptionist
You're booked for 9:00 am. I'll read you a confirmation number.
L-1042Lead saved
APT-1042Visit booked for Wednesday 9:00 am
You were at dinner.
Play the call again

What that call left in your system

Tue 7:42 pm
Answer every call.
The receptionist picks up your business line, asks what's wrong and where, and saves it as a lead. Emergencies, and callers who ask for a person, are transferred to you. Robocalls get hung up on.
The Leads screen with a new lead from the call: name, reference L-1042, the problem, and what to do next.
Harbor Home ServicesGesser OS · Workspace
Customers & sales / Leads
Leads
+ Log a lead
34To answer2Hot1Emergencies56New today
Dana WhitfieldHotjust now
L-1042Plumbing · Ceiling leak · VentnorElectrical · Tripping breaker · AbseconCleaning · Office deep clean · NorthfieldHVAC · No heat · MargatePainting · Interior, first floor · LinwoodLandscaping · Irrigation · Somers Point
“Water through the kitchen ceiling.” Upstairs bath.“Breaker won't stay reset.” Kitchen circuit.“Deep clean before we reopen.” Two floors.“No heat since last night.” House at 58.“First floor before we move in.” Four rooms.“Left side won't come on.” Zone three.
Next Visit booked for Wed 9:00 am
NewCalls · answered by the receptionist
Marcus Hill2 h ago
L-1041Drain backing up · AbseconOutdoor lights out · NorthfieldMove-out clean · MargateRooftop unit tune-up · LinwoodDeck staining · Somers PointHedge trimming · Ventnor
Tue 7:43 pm
Book the visit.
The visit lands in a slot that was really open, and the customer leaves the call with a confirmation number. You wake up to a morning that's already planned.
The Calendar screen for Wednesday with the 9:00 am slot filled by the new visit and its confirmation number.
Harbor Home ServicesGesser OS · Workspace
Schedule / Calendar
Wednesday
Day
8:00
9:00
Ceiling leak, upstairs bathKitchen breaker trippingWalkthrough, office deep cleanNo heat, furnaceEstimate walk, interior paintIrrigation zone not runningDana WhitfieldAPT-1042Confirmation 482-7155
10:00
11:00
Drain backing upOutdoor lights outMove-out cleanRooftop unit tune-upDeck stainingHedge trimmingMarcus Hill
1:00
Open
Confirmation email sent to the customer.
Wed 9:00 am
Run the job.
One work order on your tech's phone: notes, photos, what was done at that address before, and an estimate from your own price book that the customer approves from a link.
The work order screen: the job's progress, a technician note, and an estimate with two lines from the price book that the customer approved.
Harbor Home ServicesGesser OS · Workspace
Work orders / WO-1042
Ceiling leak, upstairs bathKitchen breaker trippingWalkthrough, office deep cleanNo heat, furnaceEstimate walk, interior paintIrrigation zone not running
WO-1042
1. Lead
2. Visit
3. On site
4. Estimate
5. Approved
6. Invoice
Note from the field
Supply line failed at the upstairs toilet. Shutoff valve seized. Drywall wet below.Breaker trips under load. Scorched receptacle behind the refrigerator. Circuit isolated.Two floors, about twenty desks. Carpet in the conference rooms, tile in the break room.Igniter cracked, no flame. Filter clogged. Furnace locked out on arrival.Four rooms and a hallway. Patch two walls in the dining room. Ceilings stay as they are.Zone three valve not opening. Solenoid dead. Two heads clogged near the fence.
Photos added · Upstairs bathroomPhotos added · Main panel, garagePhotos added · Second floorNameplate photo added · Furnace, basementPhotos added · Dining roomPhotos added · Valve box, side yard
Estimate EST-1042SentApproved by customer
Toilet supply line and shutoff valveReceptacle and breaker replacementDeep clean, two floorsHot surface igniterInterior walls, four roomsZone valve solenoid from price book
Labor, plumbingLabor, electricalCarpet extraction, conference roomsLabor, heatingWall patching, dining roomLabor, irrigation from price book
Diagnostic credited to this repair
Diagnostic credited to this repair
Diagnostic credited to this repair
Diagnostic credited to this repair
Wed 11:40 am
Get paid.
An invoice with a pay link from your own Stripe account. It says paid when the payment lands, not when somebody types it in. If it sits, reminders go out on a schedule you can pause.
The invoice screen changing from still to collect to paid, with the linked lead, visit, work order and estimate underneath.
Harbor Home ServicesGesser OS · Workspace
Finance / Invoices / INV-1042
Still to collectPaid in full
Invoice INV-1042
Dana Whitfield · Work order: Ceiling leak, upstairs bathKitchen breaker trippingWalkthrough, office deep cleanNo heat, furnaceEstimate walk, interior paintIrrigation zone not running
Paid
Invoice emailed with a pay link10:22 am
Customer opened the pay link11:38 am
Card payment received11:40 am
Linked records
L-1042APT-1042WO-1042EST-1042INV-1042

Next morning, your AI team clocks in.

Bring your own AI team

MuseLeadsNothing in handHas the job
ChatGPTEstimatesNothing in handHas the job
ClaudeVisitsNothing in handHas the jobWaiting for your OK
GrokMarketingPaused by you

Muse
Logged a follow-up note on a lead that had gone quiet.
Muse to ChatGPT
Passed along a request for an estimate.
ChatGPT
Drafted the estimate from your price book.
ChatGPT to Claude
Passed along a request to book the visit.
Claude
Wants to book Thursday 1:30 pm. The customer would get an email, so it waits for you.
Approved by you
Booked under your name. Confirmation email sent.

You already use ChatGPT, Claude, Grok or Muse. Connect them to your business and they work inside Gesser OS, hand work to each other, and you watch all of it from one screen.

Nothing goes out without your OK.
Anything a customer would see or receive waits for you: a visit, a published page, a changed phone number. You approve it or you don't.
No AI touches the money.
No AI app charges a card, sends an invoice, issues a refund or buys anything. That stays with people.
Every change has an Undo.
Each thing an app does is logged under the name of the person who connected it. Pause one app, or all of them, with one switch.

Works with the AI apps that support connectors. You choose what each one is allowed to do.

11 things you get on day one

Receptionist on your phone line
Answers, takes the job down, offers open times and transfers emergencies to you.
AnsweredBusiness line · 7:40 pm
CallerThere's water coming through the kitchen ceiling, right under the upstairs bathroom.Half the kitchen went dead and the breaker won't stay reset.We need the office deep-cleaned before we reopen on Monday.The heat quit overnight and the house is down to 58.We just bought the house and want the whole first floor painted before we move in.The sprinklers on the left side of the yard stopped coming on.
ReceptionistI can put someone on the schedule for tomorrow. I have 9:00 or 1:30.
L-1042Lead saved · visit booked
Website chat
The same assistant on your site. It quotes your diagnostic fee from your catalog and never makes up a price.
Leads
Every request with where it came from and what to do next.
Dana WhitfieldHotjust now
L-1042Plumbing · Ceiling leak · VentnorElectrical · Tripping breaker · AbseconCleaning · Office deep clean · NorthfieldHVAC · No heat · MargatePainting · Interior, first floor · LinwoodLandscaping · Irrigation · Somers Point
Next Visit booked for Wed 9:00 am
NewSource: phone call
Marcus Hill2 h ago
L-1041Drain backing up · AbseconOutdoor lights out · NorthfieldMove-out clean · MargateRooftop unit tune-up · LinwoodDeck staining · Somers PointHedge trimming · Ventnor
Calendar and visits
Book, move or cancel a visit. The customer gets an email when it changes.
Work orders
Visits, notes, parts, estimates, invoices and payments on one page.
Ceiling leak, upstairs bathKitchen breaker trippingWalkthrough, office deep cleanNo heat, furnaceEstimate walk, interior paintIrrigation zone not running
WO-1042
1. Lead
2. Visit
3. On site
4. Estimate
5. Approved
6. Invoice
Note from the field
Supply line failed at the upstairs toilet. Shutoff valve seized. Drywall wet below.Breaker trips under load. Scorched receptacle behind the refrigerator. Circuit isolated.Two floors, about twenty desks. Carpet in the conference rooms, tile in the break room.Igniter cracked, no flame. Filter clogged. Furnace locked out on arrival.Four rooms and a hallway. Patch two walls in the dining room. Ceilings stay as they are.Zone three valve not opening. Solenoid dead. Two heads clogged near the fence.
Price book
Sections and SKUs, with bulk upload from a spreadsheet and a review tray before anything goes live.
RepairsService callsCommercialHeatingInteriorIrrigationPrice book
- Supply line and shutoff valveReceptacle replacementDeep clean, per floorHot surface igniterInterior walls, per roomZone valve solenoid
- Drain cleaning, main lineBreaker replacementCarpet extractionFurnace tune-upWall patchingSprinkler head replacement
- Water heater flushPanel inspectionInterior windowsFilter changeTrim and doorsSpring start-up
Review traySpreadsheet upload waits for your OK
Estimates and invoices
One calculation for both, an approval link, and a pay link from your own Stripe account.
Estimate EST-1042SentApproved by customer
- Toilet supply line and shutoff valveReceptacle and breaker replacementDeep clean, two floorsHot surface igniterInterior walls, four roomsZone valve solenoid
- Labor, plumbingLabor, electricalCarpet extraction, conference roomsLabor, heatingWall patching, dining roomLabor, irrigation
Invoice INV-1042
Paid
Equipment by location
Each unit, where it lives, its service history and its photos.
Quizzes and landing pages
For your ads, with leads and money counted by campaign.
Spring campaignResults by campaign
- Leads
- Booked
- Won
- Collected
AI connections
Permissions per app, an approval inbox, and a log with Undo.
AI connectionsWhat each app can do
- ChatGPTEstimatesWorks on its own
- ClaudeVisitsAsks you for everything
- GrokMarketingPaused
LogEvery change listed, with Undo
Roles
Owner, admin, manager, dispatcher and technician, with two-step login for owners.
TeamWho can do what
- OwnerEverything · two-step login
- ManagerOffice and schedule
- DispatcherCalls, leads and calendar
- TechnicianTheir own work orders

How you start

Create your account
Your company name and your trade.
Paste your website
Gesser OS proposes your service catalog and prices for you to review and edit.
Turn on your line
Get a phone number, forward your business line to it and start taking requests.

Built in the field

Gesser OS was built by Sergio Brito, an HVAC and commercial refrigeration technician, to run his own company: Gesser Services LLC, Atlantic City, NJ. Every feature here is used on real jobs before it reaches you.

The phone is going to ring again tonight.

Start the trial and forward your line, or write to us and we will set it up with you.

Start your trial See pricing Write to us

14-day trial, no card.

Run it again from 7:40 pm

The phone rings at 7:40 pm.It gets answered.

Tuesday, 7:40 pm. One call, as it happens.

What that call left in your system

Answer every call.

Book the visit.

Run the job.

Get paid.

Bring your own AI team

Nothing goes out without your OK.

No AI touches the money.

Every change has an Undo.

11 things you get on day one

Receptionist on your phone line

Website chat

Leads

Calendar and visits

Work orders

Price book

Estimates and invoices

Equipment by location

Quizzes and landing pages

AI connections

Roles

How you start

Create your account

Paste your website

Turn on your line

Built in the field

The phone is going to ring again tonight.