If you are looking for the best mobile app for sending invoices on site, it is usually because the invoice keeps losing to the drive home. The job finishes in a driveway, a basement or a client's office, the invoice needs the laptop, and the laptop is at home. So it goes out on Friday, or the Monday after.
The short answer: the best app for sending invoices on site is one that works where you actually stand, sends a real invoice in a few taps, keeps chasing it after you drive away, and behaves the same on iPhone and Android. Billbooks, Invoice2go, FreshBooks, Wave, QuickBooks Online, Zoho Invoice, Square Invoices and Jobber all send invoices from a phone. None of the eight documents creating invoices with no signal, so if your sites have none, that is the test to run first.
Is this you?
- You finish a job, say you will send the invoice tonight, and it goes out three days later.
- You keep a notes app or a paper pad of jobs to invoice later, and some of them never make it.
- Your invoicing tool has an app, but you only use it to check things because writing an invoice on it is fiddly.
- You have stood in a basement or a rural yard waiting for one bar of signal so the invoice would send.
- You sent an invoice by text from the job, and nothing ever chased it.
Why the invoice waits
Almost nobody delays invoicing on purpose. It waits because the work finishes somewhere that is not the desk, and the invoice was built for the desk. It is common, too. In our payment-advice study: About 21.9% of invoices whose lines carry their own work dates go out more than a week after the work (3,027 of 13,803), and 7.4% more than a month after. (Source: Billbooks payment-advice study.)
That delay is not admin time. It is added to the front of a wait that was always going to happen, because the clock only starts when the invoice goes out. The typical invoice is paid 9 days after it is issued; one in ten takes 57 days or longer. (Source: Billbooks invoice data.) Nine days after it is sent, not nine days after the job. A week of not sending is a week you add yourself.
Put a yearly figure on the days your money waits
Enter what you invoice in a year and how late it typically arrives. The calculator shows what that money sitting with clients costs you, plus the hours spent chasing it, which is the number to weigh any app against.
Four tests for an invoicing app on site
App store screenshots all look alike. These four are what separate an app you will actually use on a job from one you will only open to look things up.
1. Does it work where you work?
Most invoicing apps are a window onto an online account, so no signal means no invoice. Some field-service tools can save a draft offline and send it when you reconnect. Find out which kind you have before you are standing in a plant room with a client waiting.
2. Is it a real invoice in a few taps?
Pick the client, add the lines, send. If adding a saved item, a discount or a note takes a desktop, you will end up writing a placeholder on the phone and fixing it at home, which is the delay again with an extra step. Check that the invoice from the phone carries the same numbering, branding and terms as one from the desk.
3. Does it keep chasing after you leave?
Sending is half of it. The other half is the reminder that goes out a week later without you remembering. Check whether automatic reminders are on your plan, and whether they still work for the way you send from site. On some apps an invoice sent by text message gets no automatic reminders at all.
4. Is it the same app on iPhone and Android?
If anyone else on your team raises invoices, they may not carry the phone you do. Check both stores, the minimum operating system each needs, and what the app leaves to the desktop.
Which apps do what
From each company's own help and product pages, read in October 2026 and linked beside each entry. We list only what we checked, so a feature that is not mentioned here has not been checked, not ruled out. Where a company documents nothing about working offline, we say so rather than guess.
- Billbooks runs on iPhone (iOS 15.6 or later) and Android, and the app is included in every plan with no separate charge. On the phone you pick the client, add hours and parts, a discount, shipping and a note, take a signature on screen if the job needs one, and send an invoice with your own numbering and branding. Automatic past-due reminders are on every paid plan. It is one account, so an invoice raised on site is on the web the moment you open it. It needs a connection to send an invoice or load your data, the same as the web app, so it is not a no-signal tool. Scanning paper with the camera and Xero or QuickBooks sync are still web only. See the Billbooks mobile app.
- Invoice2go is built around the phone: its features page says it is available on the web, iOS and Android, that you can invoice customers on the go, and it lists automated overdue invoice reminders. Its features page says your information is synced across your devices and says nothing about working offline (Invoice2go features). See Billbooks vs Invoice2go.
- FreshBooks pitches its app for exactly this job, sending a client an invoice from their own office, and tells you when an invoice has been viewed or has become overdue. It needs iOS 15 or Android 7.0 or later, and FreshBooks says some features, such as reporting, are desktop only. Its mobile page does not mention offline use (FreshBooks mobile apps). See Billbooks vs FreshBooks.
- Wave has an app on iOS and Android for creating and sending invoices on the go, with instant notifications when an invoice is viewed, becomes due or is paid. Automatic payment reminders are, in Wave's words, available to Pro Plan subscribers and online payments users. On connectivity, Wave says its tools are web based and you just need an internet connection (Wave mobile). See Billbooks vs Wave.
- QuickBooks Online has a mobile app, and its automatic reminders let you set up to three email reminders, scheduled up to 90 days before or after the due date (Intuit: invoice reminders). On signal, the accepted answer on Intuit's own QuickBooks Community, from February 2023 and from a community member rather than Intuit staff, says QuickBooks Online requires an internet connection for both the browser and the mobile versions (QuickBooks Community). We found nothing newer from Intuit saying otherwise. See Billbooks vs QuickBooks.
- Zoho Invoice is the one company that answers the offline question directly in its own help: it says Zoho Invoice cannot currently be accessed offline and you have to be connected to the internet to use the app (Zoho Invoice: can I use it offline). See Billbooks vs Zoho Invoice.
- Square Invoices lets you send an invoice from the phone by email, text message or a shared link, and set payment reminders while you build it. The catch for on-site work is in Square's own help: automatic reminders are not supported when you choose text message as the delivery method. So the fastest way to send from a driveway is also the one that never gets chased (Square: send and manage invoices). On offline invoicing, Square's community moderator pointed a seller asking for it to a feature request in November 2024 (Square Community). See Billbooks vs Square Invoices.
- Jobber is field-service software rather than an invoicing tool, so it is on many trade shortlists. Its help centre says that when the app has no internet connection it shows a message telling you that you are offline and since when, and it does not say that invoices can be created while you are (Jobber: app troubleshooting). If offline invoicing matters to you, ask Jobber directly before you buy.
If your sites have no signal
None of the eight above documents creating an invoice with no connection. If that is your daily reality, you are shopping in a different category: field-service management apps, some of which do work offline. FieldPulse is one example that documents it in detail. Its help says you can create new estimates and invoices offline and they sync automatically when you reconnect, but you cannot collect a payment, preview a new draft or collect signatures on it until you are back online (FieldPulse: offline mode). Even offline-capable tools send the invoice when you get signal, not before, so the real gain is that the invoice is written while the job is fresh.
What that adds up to
For most people who invoice from site, signal is not the problem; habit is. Phone signal at the job is usually enough, and any of these apps will send a real invoice from the driveway. The differences are smaller and more practical: whether the reminders survive the way you send, whether the invoice from the phone is the same invoice as the one from the desk, and whether the feature you need is on your plan.
If you send by text because it is quickest, check what happens to reminders on your app. If your team mixes iPhone and Android, check both store listings and the minimum operating system before you commit everyone. And if you genuinely work out of signal every day, look at an offline-capable field-service app and accept that you are paying for more than invoicing.
What to do now, with what you already have
You do not need a new app to stop the invoice waiting. On the next job, send the invoice before you start the engine. If your current tool has an app, install it and send one real invoice from the phone, then check three things back at the desk: it carries your normal number and branding, a reminder is scheduled on it, and it arrived the way you meant it to.
If you have no app at all, the free invoice generator works in a phone browser with no account, which is enough to stop a job waiting for the laptop while you decide.
What to do if the invoices are already stacked up
Clear the backlog oldest first, today, because every one of those invoices has a clock that has not started. Do not apologise for the delay in the invoice itself; send it with the job date on the lines and your normal terms. Then set reminders on the ones you send, so the backlog does not turn into a second backlog of chasing.
How to stop it happening again
Make the invoice part of finishing the job, not part of the evening. Save your common items and rates in the tool so a job invoice is a few taps. Leave terms at due on receipt unless a client has agreed otherwise. Turn on automatic reminders once, so nothing depends on you remembering on a Friday.
If you want one account for the phone and the desk, the Billbooks mobile app is included in every plan: you write and send the invoice on site, take a signature if the job needs one, and the automatic past-due reminders chase it after you leave. It needs a signal to send, so it removes the drive home, not the dead spot.
Two free tools for getting the invoice out before you leave the job
Frequently asked questions
What invoicing software has the best mobile app for sending invoices on site?
The best one is the app you will actually use on a job, which comes down to four tests: it works with the signal you have, sends a real invoice in a few taps, keeps sending automatic reminders after you leave, and behaves the same on iPhone and Android. Billbooks, Invoice2go, FreshBooks, Wave, QuickBooks Online, Zoho Invoice, Square Invoices and Jobber all send invoices from a phone, and none of the eight documents creating invoices with no connection.
What invoicing software works offline or on mobile?
All eight invoicing apps we checked work on mobile, on both iPhone and Android. Working offline is rarer. Zoho Invoice says plainly in its help that it cannot be used offline, Wave says you need an internet connection, and Billbooks needs a connection to send. If you need to write invoices with no signal, look at field-service apps such as FieldPulse, which documents creating invoices offline and syncing them when you reconnect.
Is there an invoicing app that sends automatic payment reminders and works on iPhone?
Yes, several. Billbooks includes automatic past-due reminders on every paid plan and runs on iOS 15.6 or later. QuickBooks Online lets you schedule up to three automatic email reminders. Wave offers automatic reminders to Pro Plan subscribers and online payments users. Square Invoices supports reminders too, but not on invoices sent by text message, so check how you send.
Can I send an invoice from my phone without internet?
Not with most invoicing apps. They are windows onto an online account, so the invoice goes when you have signal. Some field-service apps let you write the invoice offline and send it automatically once you reconnect, which at least gets it written while the job is fresh. Even then, the client only receives it when your phone is back online.
Does an invoice sent from the app look the same as one from my computer?
It should, and it is worth testing. In an app that is part of the same account, the invoice carries your normal numbering, branding and terms, so the client cannot tell which device you used. Send yourself one test invoice from the phone and compare it with one from the desk before you rely on it.
Do I need a separate app for invoicing on site if I already use accounting software?
Not necessarily. QuickBooks Online, Wave and Zoho Invoice all have their own apps. The questions are whether the features you need on site are on your plan, whether reminders work the way you send, and whether the app needs anything done at the desk first. If those fail, a dedicated invoicing app alongside your accounting software is a common setup.
