Overview

BillingEngine creates XRechnung and ZUGFeRD invoices compliant with EN 16931 and supports tax validation. Accepted quotes can turn into invoices, and reminders can be sent at several dunning levels, covering a useful slice of routine billing without suggesting a broader accounting suite.

Every plan includes an unlimited email inbox for incoming e-invoices, independent of its monthly document allowance. Receipt recognition extracts amount, date, tax rate and supplier, then matches the receipt to an expense. DATEV, CSV, XLS, XML and PDF exports are also available on every plan, a strong handoff option for teams working with different bookkeeping processes. The REST API covers customers, invoices and payments.

BillingEngine says data is encrypted in transit, stored on servers in Germany and archived in a GoBD-compliant way. For AI receipt recognition, it says only the document is sent encrypted to OpenAI, its contents are not used to train models, and the document remains on its Frankfurt server. These assurances may matter to businesses handling sensitive financial records, though each team should judge them against its own requirements.

Key features

Structured e-invoicing: EN 16931-compliant XRechnung and ZUGFeRD formats make the product relevant to businesses needing those standards, rather than merely PDF billing.
Quotes and dunning: Accepted quotes convert to invoices, and reminders support several dunning levels, reducing friction in common billing steps.
Receipt capture: Recognition pulls key fields from receipts and matches them to expenses; this is useful for expense records, while the monthly receipt cap can constrain heavier users.
Exports and API: Broad export formats plus an API for customers, invoices and payments provide options for accounting handoff and integration with existing systems.
Incoming e-invoices: The unlimited email inbox is included on every tier, so inbound volume does not use the capped invoice, quote or receipt quotas.

Pricing

The free tier costs 0.00 EUR per free, billed monthly, and allows 3 invoices, 3 quotes and 3 receipts per month for 1 user. Its unlimited incoming e-invoice inbox and exports make it useful for a very small operation or light evaluation, but the quotas are too restrictive for regular billing beyond a handful of documents.

Basic costs 6.00 EUR per month, billed plus VAT. It raises each monthly quota to 30 and allows 2 users. This is the practical entry point for a small business with predictable, modest volume; the caps remain a meaningful ceiling, and the price excludes VAT.

Premium costs 12.00 EUR per month, billed plus VAT, and removes the invoice, quote and receipt limits while supporting 5 users. It is the clearest choice for teams whose document flow has outgrown Basic, though the five-user ceiling may not fit larger groups. Priority email support is included as a plan feature, with requests often answered the same business day.

Platforms

BillingEngine is a cloud service with web and API access. The API covers customers, invoices and payments, making it relevant where those records need to connect with an existing stack.

Who it's for

BillingEngine is best suited to German freelancers and small businesses that need structured e-invoices, quotes, reminders, receipt handling and accounting exports in one workflow. Teams needing only occasional invoicing can start free, while predictable monthly volume may fit Basic. Businesses with higher volume should budget for Premium; those seeking broader accounting functionality should compare their requirements before choosing it.

Pros and cons

Pro: XRechnung and ZUGFeRD support with EN 16931 compliance directly addresses structured e-invoicing needs.
Pro: Unlimited incoming e-invoice email is included even on the free tier, separate from its small outbound document allowances.
Pro: DATEV, CSV, XLS, XML and PDF exports on every plan give users several routes for accounting handoff.
Con: Free allows just 3 invoices, quotes and receipts monthly, limiting it to very light use.
Con: Basic still caps each document type at 30 per month, so growing teams may need the more expensive Premium tier.
Con: Premium supports up to 5 users, which can rule it out for larger teams.

Alternatives

For a different e-invoicing option, compare the Electronic Invoicing Software directory; for broader invoice-tool comparisons, see Invoicing software.

B2Brouter has a free plan billed forever with up to 10 contacts, 24 transactions per year and 1 user; choose it if that smaller annual allowance suits your needs.
Billit offers Android and iOS apps as well as web and API access; its free license sends Peppol e-invoices for sales invoices with limited functionality, a fit if mobile access or Peppol sending is the priority.
PeppolSoft offers a free Buyer plan with receiving and a web portal; consider it when receiving is the central need.
ONESOURCE Pagero is another freemium option, offered by Thomson Reuters, whose work includes compliance, tax and legal solutions.
Unimaze is a paid alternative with Android and iOS apps as well as web and API access.
Vertex e-Invoicing uses custom pricing; country and jurisdiction coverage varies, and VAT compliance periodic reporting is an add-on.
Avalara VAT Registration is a paid option without a free plan; pricing is custom.
Domibus is a free, self-hosted alternative with API access.

Verdict

BillingEngine is a strong fit for German freelancers and small businesses that need compliant structured invoices, flexible exports and a route from quotes through reminders. Its key advantage is the combination of those workflows with an unlimited incoming e-invoice inbox across plans. Look elsewhere if your document volume exceeds Basic’s quotas, your team is larger than Premium’s five users, or your needs extend beyond the billing and accounting functions it provides.

	BillingEngine	Sleek Bill
Free plan	Yes	Yes
Free trial	No	No
Paid from	€6/mo	$5.75/mo
Open source	No	No
Platforms	api, Web	Web, Windows, macOS
Free plan	Yes	Yes
Recurring invoices	—	Yes
Payment reminders	—	Yes
Multi-currency invoicing	—	Yes
Client portal	—	Yes

BillingEngine vs Sleek Bill

BillingEngine

Sleek Bill