Certio vs Zerta: One-Off Android App or Full Cert Suite?

Zerta is an Android-only certificate app from a solo electrician's firm in the Scottish Borders. It is free to create and preview certificates, then £6.99 once, with no subscription, to export, share and brand the PDFs. Certio is an app for iPhone, Android and the browser with a free plan and paid plans at £4.99 and £9.99 a month, built around AI board-photo schedules, voice dictation and camera reading of a Megger MFT-X1. Choose Zerta if you are on Android, issue a modest number of certificates and want the lowest cost going. Choose Certio if you want the schedule filled for you, PAT records, or one login across devices. Facts checked 3 October 2026.

What is Zerta?

Zerta is an Android app for issuing BS 7671 certificates, aimed by its own description at solo electricians and small UK firms. The Google Play listing names the developer as James Duffield Electrical Services Ltd, company number SC859029, incorporated on 14 August 2025 with a registered office near Kelso and shown as active on Companies House on 3 October 2026. Zerta's "our story" page describes a small, family-run firm with one electrician on the tools, who built the app in the evenings after being frustrated by the features and ongoing costs of what was available.

Zerta's website and FAQ state the following, and this comparison sticks to what they say:

• Three certificate types: Electrical Installation Certificate, Minor Electrical Installation Works Certificate and EICR.
• A free version that creates and previews unlimited certificates.
• Zerta Pro, a £6.99 one-off in-app upgrade that unlocks exporting, printing and sharing the finished PDF, logo branding, data backups and duplicating a previous certificate. The FAQ says it is valid for the lifetime of your Google Play account, with no subscription, tokens or monthly fees.
• Fully offline working. You only need a signal to send the finished PDF.
• No online account. Certificates are stored on the device.
• Android only for now, designed first for a phone.
• Not endorsed by or affiliated with the IET, NICEIC, NAPIT, SELECT or BSI.

Google Play showed 100+ downloads and a last update of 1 July 2026 when checked.

What is Certio?

Certio is an electrical certification app from Certio Software Ltd, built by a working UK electrician. It produces EICRs, EICs, Minor Works certificates and PAT testing records to BS 7671, and it runs as an iPhone app, an Android app and in a web browser with one login.

The difference is how the data gets in. You photograph the consumer unit and the AI drafts the circuit schedule for you to check. You dictate readings by voice. If you use a Megger MFT-X1, Certio reads the instrument's screen live through the phone camera; that works with the MFT-X1 only, with more instruments to follow. For observations it suggests C1, C2, C3 or FI wording that you accept or edit. You remain the inspector and the signature is yours. There is a fuller summary on the Certio fact sheet.

How do Certio and Zerta compare side by side?

Sources: zerta.co.uk (home page, FAQ, terms, story), the Google Play listing, Companies House and certio.uk, all checked 3 October 2026. "Not described" means the vendor's website does not mention it. It is not a claim that the feature is absent, so ask the vendor if it matters to you.

What does each one cost over one, three and five years?

On price there is no contest.

Figures assume today's published prices hold.

The free tiers are not the same thing, though. Zerta's free version lets you build and preview a certificate but not export or share it, so in practice you pay the £6.99 before the first certificate goes to a client. Certio's free plan issues certificates with a small Certio mark on the PDF and the AI features switched off.

So the honest question is not which is cheaper. It is whether Certio's data-entry tools are worth roughly £60 a year to you. Starter works out at about 16p a day. If you issue a certificate a month, probably not. If you are doing several EICRs a week, the typing is where your evenings go, and that is the cost to weigh. For the wider market, see Best Electrical Certification Software UK 2026.

How does the on-site workflow differ?

A ten-way board at 15 or more columns per circuit is upwards of 150 entries on a schedule of test results before you write a single observation. Both apps let you fill that in on the phone while you are still on site.

With Zerta, every entry is typed. Its strengths are that it opens without a login, works with no signal at all, saves your own details for reuse and, on Pro, duplicates a previous certificate as a starting point. Duplicating is handy for repeat visits, as long as you re-test and do not carry old readings forward.

With Certio, the board photo gives you a draft circuit schedule to check against the installation, you speak readings as you take them, and suggested observation wording saves you composing each one from scratch. An AI draft is still a draft, so check it against the board before you sign.

Neither app changes what you test or in what order. IET Guidance Note 3 sets out the sequence, and How to Fill In a Schedule of Test Results goes through the columns one by one. For classification, Electrical Safety First's Best Practice Guide 4 is the reference most inspectors work to, and EICR observation codes explained and How to write EICR observations cover the wording.

Where are your certificates kept, and does it matter?

It matters more than most people think. The Building Safety Act 2022 extended the limitation period under the Defective Premises Act 1972 to 15 years for dwelling work completed after 28 June 2022. A certificate you issue today may need to be found in 2041.

Zerta stores certificates on the Android device and needs no account. That is good for privacy, but it puts the backups in your hands. Zerta's FAQ lists data backups as a Pro feature, and its website does not describe syncing between devices. If you go this route, export every finished PDF to storage you control, and test restoring to a new phone before you need to.

Certio keeps certificates against your account, so the same records open on the phone, a tablet and the laptop, and a broken handset does not take your paperwork with it. The trade-off is that you need an account.

Whichever you choose, client names and addresses are personal data under UK GDPR. Electrical certificate retention and GDPR covers how long to keep what, and Digital vs paper electrical certificates covers what the schemes accept.

Which one is ready for Amendment 4?

BS 7671:2018+A4:2026 was published on 15 April 2026, and Amendment 2 is withdrawn on 15 October 2026. After that date, new work should be designed and certified to A4. NICEIC has said that work designed before 15 October 2026 may be completed to the previous standard, so there will be a short period with both in circulation.

Zerta's website carries a note dated 15 April 2026 saying its Android app supports Amendment 4, and a support page saying it covers BS 7671:2018 with Amendments 2, 3 and 4. Certio's certificates follow the current BS 7671:2018 model forms, and the app is being updated for Amendment 4 ahead of the withdrawal date.

Do not take either statement, or any software vendor's, on trust. Generate a test certificate, check the edition stated on it, and compare the layout with the model forms in Appendix 6 of the edition you are certifying to.

Who should choose which?

Zerta is the better fit if you use an Android phone, you issue a few certificates a month, you are happy typing readings, and you do not want another monthly bill. It is also a sensible pick if you want nothing stored online.

Certio is the better fit if you use an iPhone or want to finish certificates on a laptop, you do enough EICRs that typing schedules eats your evenings, you own a Megger MFT-X1, or you need PAT testing records alongside the BS 7671 forms. The Pro plan adds quotes and invoices if you want those in the same place.

Landlord work is a fair test of both. In England, the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 require an inspection at least every five years, GOV.UK guidance says the tenant must get the report within 28 days, and councils can fine up to £40,000. In Scotland the repairing standard also expects an EICR at least every five years. That favours whichever app gets you from last test to sent PDF fastest. See Landlord EICR regulations in England and EICR landlord requirements in Scotland and Wales.

For a buying checklist see what to look for in electrical certification software, or compare Certio vs TestFast and Certio vs U Certify Electrics.

How Certio helps

Certio produces the EICR, EIC, Minor Works certificate and PAT records on the BS 7671 model forms and turns them into branded PDFs. Photograph the consumer unit and the circuit schedule drafts itself; point the phone camera at a Megger MFT-X1 and the reading goes straight into the schedule of test results, or dictate it while your hands stay on the probes. Suggested observation wording with the regulation reference is there for you to check and confirm. The judgement stays yours; the typing goes. Starter is free for 7 days, then £4.99 a month.

Written by the Certio team. Last checked 3 October 2026.