Best App for Gas Engineers UK 2026
A fair, feature-by-feature comparison of the six apps UK gas engineers are actually choosing between in 2026, covering pricing, offline mode, CP12 handling and real trade-offs for each one.
Best App for Gas Engineers UK 2026
Six real apps UK gas engineers are actually choosing between right now, compared on pricing, offline reliability, CP12 handling and the trade-offs each one carries, not just the features they market.
By Daniel Sedgwick, Founder and Managing Director of Checker
Search “best app for gas engineers UK” and the honest answer is that no single app wins on every measure. Some are built to produce a CP12 as fast as possible and stop there. Some are full job management platforms that happen to handle gas certificates well. Some scale their price with every extra engineer on the team; others charge the same whether it’s one van or five. A few work perfectly offline in a signal-dead plant room. One flatly doesn’t.
This guide compares six apps UK gas and heating engineers are genuinely using in 2026: Gas Engineer Software, Gas Certificate App, Checker, Tradify, GasCert (by iCertifi), and Commusoft. Each entry covers the real pricing model, how it actually handles gas safety compliance, one genuine strength, one genuine trade-off, and what independent reputation signal exists for it. None of these six is the right answer for every business. The goal here is to make the actual differences clear enough that the choice is obvious for your own situation.
Key takeaways
- All six apps can produce a CP12 and related gas certificates; none of them submits directly to Gas Safe Register, so the real differentiator is breadth and automation around the certificate, not the certificate itself.
- Pricing models differ more than headline numbers suggest: Gas Engineer Software, Tradify and Commusoft charge per user per month, Gas Certificate App and GasCert charge a flat fee per user role, and Checker is the only one with genuinely flat tier pricing that doesn’t scale with headcount.
- Offline capability is close to table stakes among the gas-focused tools, Checker, Gas Engineer Software, Gas Certificate App, Commusoft and GasCert all state it works with no signal, but Tradify’s own help centre confirms it does not work offline at all.
- Commusoft is the only one of the six built specifically for teams of 6 or more, with no self-serve free trial; the other five all work for a sole trader from day one.
On this page
Gas Engineer Software (GES)
Gas Engineer Software runs three tiers, all priced per user per month: Starter at £19, Core at £25, and Pro at £32, each with a slightly cheaper annual rate. It’s genuinely per-seat pricing, so a two-person firm on Core pays £50/month, not a flat fee. There’s no setup cost, no contract, and a 14-day free trial with full feature access and no card required.
Gas compliance is a real strength here, not an afterthought. GES lets engineers create, issue and store CP12 landlord gas safety certificates, boiler service records and gas tightness test records digitally from mobile, all stored with full history and accessible from both the app and a web portal. The app works offline, including certificates, so a signal-dead plant room isn’t a blocker. Automated service reminders and Gas Safety deadline notifications are built in from the Core tier up.
Strength: Xero integration on the Pro tier is a true two-way sync, changes made in either system reflect automatically in the other, which is a genuinely deeper accounting connection than most competitors on this list offer for any provider.
Trade-off: Accounting integrations, including that two-way Xero sync, only unlock on the £32/user/month Pro tier, and QuickBooks and Sage sync outbound only in both directions, not the deeper two-way link Xero gets. Per-user pricing also means the total cost climbs steadily as a team grows, unlike a flat-fee model.
Reputation signal is solid and well-sampled: 4.7 out of 5 on the Apple App Store from over 1,500 ratings, and 4.4 out of 5 on Google Play from 447 ratings, both pulled directly from each store’s own structured rating data.
Checker
Checker runs three tiers at a genuinely flat monthly rate that doesn’t scale with team size: LITE at £10.99/month, PRO at £19.99/month, and PRO+ at £25.99/month, plus the option to add sub-users on PRO+ at £10.99/month each. A two-person firm on PRO pays the same £19.99 as a solo engineer on the same tier, that’s the core structural difference from every per-user competitor on this list. There’s a 30-day free trial with no card required, confirmed on Checker’s own About page and app store listings, though it isn’t mentioned on the pricing page itself. LITE covers creating digital records, while the PRO tier adds the full back-office set on top of the certificates: a customer CRM, reminders, business analytics, accountancy integrations and a Growth Engine for chasing repeat work.
Gas and heating compliance is built into the product from the ground up rather than bolted on: CP12, boiler service records, installation and commissioning certificates, and tightness testing and purging reports are all named specifically on Checker’s gas engineer page. Certificates follow Gas Safe, OFTEC and BS7671 layouts and are accepted by landlords, letting agents, insurers and Building Control, the same “follows the standard, doesn’t submit to the registry” position every app in this comparison is in. Offline capability is stated repeatedly and specifically: forms can be completed with no signal, “even with one bar of 3G,” saved to the device, and synced to the cloud automatically once back in range.
Strength: a four-workflow Automations engine, Appointment Reminders, Quote Chaser, Invoice Chaser and Annual Service Reminder, runs on every job and customer record automatically once switched on. The Annual Service Reminder fires 11 months after a customer record is created by default and explicitly references boiler safety, OFTEC compliance and landlord gas safety certificates in its default wording, which is a broader compliance-automation set than any other app in this comparison publicly documents. Checker also confirms real hardware integration: Bluetooth data transfer from KANE flue gas analysers straight into a gas certificate, cutting out manual transcription.
Worth knowing: Checker’s app store history goes back further than the current listing alone suggests. Checker is the 2025 rebrand of Gas Checker, the same UK team and product that’s been serving gas and heating engineers since 2012. Combined across both listings, that’s a 4.24-star rating from 105 reviews, real history behind a newer-looking listing. The current “Checker” listing is still building its own review count since the rebrand, so a search today surfaces the smaller number first, but the team and the product behind it are the one gas engineers have used for over a decade.
Gas Certificate App
Gas Certificate App charges a flat £20/month per user role, whether that’s the main engineer, an additional engineer, or an admin user, with no feature-gated tiers underneath it. Every subscription level gets the same full feature set, and there’s a 14-day free trial with no card required. It’s a simpler pricing shape than a tiered ladder, though it’s still per-seat: a solo engineer and a full admin both pay the same £20, and cost still rises with headcount.
Certificate handling is the clear centre of gravity for this app. It can generate CP12s, LGSRs, oil certificates, powerflush certificates and heat pump checklists, with the app’s own marketing headlining “28 Gas & Oil Certificates” as its core pitch. Offline mode is the single most heavily marketed feature on the site: certificates, customer information and schedule can all be completed with no connection, syncing automatically once back online.
Strength: the offline claim is explicit, unhedged, and appears in the app’s own FAQ schema rather than just marketing copy, making it one of the most directly-stated offline commitments among the certificate-focused apps in this list.
Trade-off: automation is limited to a single service-due-date reminder rather than a broader workflow engine, and accounting sync is asymmetric: the app’s own FAQ describes QuickBooks as a full integration but Xero only as a “data export,” a materially shallower connection than a true sync.
Reputation signal is positive but on a smaller sample than some competitors: 4.24 out of 5 on the Apple App Store from 227 ratings, and 4.44 out of 5 on Google Play from 147 ratings, both pulled directly from each platform’s own structured data.
Tradify
Tradify’s UK pricing runs three tiers, all per user per month: Lite at £34, Pro at £37, and Plus at £44, with a Custom tier for larger teams. This is fully per-seat pricing, so a three-person firm on Pro pays £111/month. There’s a 14-day free trial with no card required and no minimum contract term.
Tradify has a dedicated gas safety certificates section with 15 digital certificate and form templates, including the Landlord/Homeowner Gas Safety Record, Service Maintenance Record, and several oil-specific forms. What it doesn’t have is any Gas Safe Register-specific tooling, no engineer ID field, no registry lookup, and there’s no automation layer wrapped around certificate or compliance events the way Checker’s Automations engine works.
Strength: SmartTools, available on the Plus tier, uses AI to extract line-item detail from photographed supplier invoices and to help draft quote and invoice descriptions automatically. It’s the only AI-assisted drafting feature confirmed across any app in this comparison, and Tradify’s template library (15 gas and oil forms, plus a separate electrical certificates set) is the largest confirmed set of certificate templates here.
Trade-off: Tradify does not work offline. Its own help centre states plainly that both the web console and mobile app depend on a live internet connection to operate, a real limitation for gas engineers who regularly work in signal-dead cupboards and plant rooms, and the opposite position from every other gas-focused app in this comparison.
Reputation signal is the strongest of any app in this comparison: 4.8 out of 5 on the Apple App Store from 2,575 ratings, and 4.82 out of 5 on Google Play from 3,022 ratings, both pulled directly from each store’s own structured rating data.
GasCert (by iCertifi)
GasCert is priced through the Apple App Store at £24.99/month, £149/year, or £490 for an annual enterprise/volume licence, and offers only a 3-day free trial, the shortest of any app in this comparison. It’s an Apple-only product: iPhone, iPad and Mac, with no Android or Google Play listing at all, which rules it out entirely for any team on Android devices.
Certificate handling is the entire focus: CP1, CP12/LGSR, breakdown and service reports, gas warning notices, gas test and purge records, and leisure industry gas safety records are all named specifically. There’s no job scheduling, calendar, quoting or invoicing anywhere on the product, this is a certificate tool, not a job management platform, and that scope is a deliberate design choice rather than a gap. Offline capability is confirmed: certificates can be completed with no data connection, with changes saved locally on the device.
Strength: GasAI, an integrated assistant described as trained on UK gas regulations, boiler manuals and fault-finding, is embedded directly in the certificate workflow. No other app in this comparison offers anything comparable, a genuinely distinctive feature for an engineer who wants diagnostic support alongside the paperwork.
Trade-off: no accounting integration of any kind, no Xero, QuickBooks or Sage, and no job management features at all beyond certificates, so it needs pairing with something else for quoting, invoicing and scheduling. It’s also Apple-only, which is a hard blocker for Android-based teams.
Reputation signal here is genuinely too thin to draw a conclusion from: the App Store listing shows 1.0 out of 5 from exactly one rating, on an app that’s only around 7 to 8 months old. That single rating shouldn’t be read as representative of quality either way, it simply reflects how new the listing is.
Commusoft
Commusoft doesn’t publish exact prices; its own pricing page names three plan tiers by name only and directs visitors to book a call. Third-party listings on Capterra, SoftwareAdvice and GetApp consistently report a starting figure of £59 per user per month. Commusoft’s own FAQ states it’s specifically designed for businesses with 6 or more staff, and multiple independent sources confirm there’s no self-serve free trial, sales run through a demo call rather than a same-day signup.
Commusoft has dedicated gas safety and CP12 functionality: landlord gas safety certificates are built through its general Digital Forms feature, with customer data auto-populating from the CRM and digital signature capture. Its mobile app is confirmed offline-capable, stating jobs and forms can be completed with no signal and will sync automatically once reconnected. No evidence was found of proactive renewal-cadence automation specifically for gas safety certificates, that’s an absence in public documentation rather than a confirmed limitation.
Strength: the widest accounting integration set of any app in this comparison. Confirmed support for Xero, QuickBooks (Desktop and Online), Sage, FreeAgent and Kashflow, a broader spread than any competitor here, useful for a growing business already committed to a particular accounting package.
Trade-off: the 6-staff minimum and sales-call-only onboarding rule it out for sole traders and very small teams entirely, and Commusoft’s own knowledge base states its accounting interface is one-way, changes made directly in the accounting package don’t flow back into Commusoft, despite some marketing copy implying fuller two-way sync.
Reputation signal is strong where it could be independently confirmed: 4.3 out of 5 on the Apple App Store from 114 ratings, and 4.7 out of 5 on Capterra from 210 reviews, both pulled directly from the platforms themselves. Its Google Play rating could not be independently verified at the time of writing.
Side-by-side comparison
The table below pulls together the verified facts from every entry above: how each app charges, whether it works offline, how it handles gas safety compliance, and who it genuinely suits best.
| App | Pricing model | Offline mode | Gas Safe / CP12 handling | Best fit |
|---|---|---|---|---|
| Gas Engineer Software | Per user/month, £19-£32 | Yes, confirmed | CP12, service records, tightness tests; follows standard layout, no registry submission | Teams wanting the most established, broadest gas-specific platform |
| Checker | Flat tiers, £10.99-£25.99/month, not per user | Yes, confirmed and specific | CP12, boiler service, installation/commissioning, tightness testing; follows standard layout, no registry submission | Businesses wanting compliance automation and flat pricing regardless of team size |
| Gas Certificate App | Flat £20/user role/month | Yes, headline feature | CP12, LGSR, oil, powerflush, heat pump checklists | Engineers prioritising certificate volume and offline reliability above all else |
| Tradify | Per user/month, £34-£44 | No, confirmed by Tradify’s own help centre | 15 gas/oil certificate templates; no Gas Safe Register-specific tooling | Teams that mainly work with signal and want AI-assisted quoting |
| GasCert (iCertifi) | £24.99/month or £149/year, Apple only | Yes, confirmed | CP1, CP12/LGSR, breakdown, gas test and purge records; certificate-only, no job management | Apple-using sole traders who just need fast, reliable certificates |
| Commusoft | From ~£59/user/month (third-party reported), 6+ staff minimum | Yes, confirmed | CP12/LGSR via Digital Forms; wide accounting integration set | Established teams of 6+ wanting the deepest accounting integration |
How to choose
Start with team size and pricing shape. A sole trader or two-person outfit pays a very different long-term price on a per-user app than on a flat-tier one; work out what a realistic team size in three years would cost on each model before comparing feature lists. Commusoft rules itself out below 6 staff regardless of feature fit.
Next, check offline reliability against where the work actually happens. If plant rooms, basements and rural signal dead zones are a regular part of the job, Tradify’s lack of offline support is a real, practical blocker, not a minor gap. Every other app in this comparison handles it.
Then decide whether certificate speed or full business management matters more. GasCert and Gas Certificate App are built to get a CP12 done fast and stop there. Checker, Gas Engineer Software, Commusoft and Tradify all wrap certificates into scheduling, quoting, invoicing and customer history, useful if the goal is running the whole business from one app rather than pairing a certificate tool with something else.
Finally, look at what happens automatically between jobs. Compliance and repeat business both depend on someone remembering to chase a renewal, a quote, or an unpaid invoice on time. Checker’s four-workflow Automations engine is the most complete version of this found across the six apps compared here; if that gap is the actual pain point, it’s worth weighing more heavily than feature-count alone.
Frequently asked questions
What’s the best app for a UK gas engineer in 2026?
It depends on business size and what matters most day to day. Gas Engineer Software is the broadest, most established option and is a strong default for most gas and heating teams. Solo engineers who mainly need fast, reliable CP12s often prefer a dedicated certificate app like Gas Certificate App or GasCert. Businesses that also want automated repeat-business chasing built around gas safety renewals, at one flat monthly price regardless of team size, are the case Checker is built for. Larger, multi-engineer operations with heavier accounting needs tend to look at Commusoft or Tradify.
Does the app work offline for gas engineers working in basements, plant rooms, or areas with no signal?
Most of the newer, gas-focused apps in this comparison do: Checker, Gas Engineer Software, Gas Certificate App, Commusoft and GasCert all state that certificates and job data can be completed with no signal and will sync automatically once a connection returns. Tradify is the exception. Tradify’s own help centre states plainly that both its web console and mobile app depend on a live internet connection to operate, which matters for gas engineers who regularly work in signal-dead utility cupboards and plant rooms.
Does it handle CP12 and other gas safety certificates properly?
All six apps in this comparison can produce a CP12 (Landlord Gas Safety Record) and related gas certificates. None of them submit certificates directly to Gas Safe Register on an engineer’s behalf; all of them produce certificates that follow the standard Gas Safe layout and are accepted by landlords, letting agents, insurers and Building Control once signed. The real differences are in breadth (job management and CRM built around the certificate, versus a certificate-only tool) and in whether renewal reminders are automated or left to the engineer to track manually.
How much does gas engineer software cost, and is it charged per user?
Pricing models vary more than the headline numbers suggest. Gas Engineer Software, Tradify and Commusoft all charge per user per month, so cost rises directly with team size. Gas Certificate App and GasCert charge a flat rate per user role rather than a tiered ladder. Checker is the only one of the six with genuinely flat, tier-based pricing that does not scale with headcount on its own core tiers, with additional sub-users available as a separate add-on rather than a per-seat multiplier.
Can I use it as a sole trader, or is it built for teams?
Gas Engineer Software, Checker, Gas Certificate App, GasCert and Tradify are all realistic for a sole trader from day one. Commusoft is the exception: its own FAQ states it is specifically designed for businesses with 6 or more staff, and it does not offer a self-serve free trial, so it is built around a sales-call onboarding process rather than a same-day sole-trader signup.
Does it integrate with Xero, QuickBooks or Sage for accounting?
Xero and QuickBooks integrations are close to standard across this list. Gas Engineer Software (Pro tier), Commusoft, Tradify and Checker all connect to Xero, QuickBooks and Sage. Gas Certificate App connects to QuickBooks directly but only offers a data export to Xero rather than a full sync. GasCert has no accounting integration at all, consistent with being a certificate-only tool. Sync direction matters as much as the connection itself: several of these integrations push data outward only, rather than syncing changes back in both directions.
What’s the difference between a certificate-only app and a full job management app, and which one do I actually need?
A certificate-only app, like Gas Certificate App or GasCert, focuses on producing and storing gas safety certificates fast, usually with little or no job scheduling, quoting, invoicing or CRM attached. A full job management app, like Checker, Gas Engineer Software, Commusoft or Tradify, wraps certificates into a wider system that also handles bookings, quotes, invoices and customer history. An engineer who mainly needs to turn round CP12s quickly may prefer the narrower tool. An engineer trying to run the whole business, including chasing repeat annual safety checks without doing it by hand, generally gets more value from the broader platform.
Is Checker a good fit alongside apps like Gas Engineer Software or Gas Certificate App?
Checker is built specifically around the same gas-and-heating compliance cycle those apps focus on, but adds a four-workflow Automations engine, covering appointment reminders, quote chasing, invoice chasing and annual service reminders, at one flat monthly price that does not increase with team size. For an engineer who already wants a dedicated gas and heating tool and also wants the admin around each job automated without extra per-seat cost, Checker is a direct, purpose-built alternative rather than an add-on to run alongside another platform.
Built for gas and heating engineers, priced flat by design
CP12s, service records, quotes and invoices, plus automated compliance and payment chasing, all at one price whether it’s one van or five.
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