eIDAS e-signature integration cost for a custom app in Amsterdam in 2026

The verdict in three sentences

Integrating e-signature through an API into a business application costs 5,000 to 15,000 EUR for simple and advanced signatures, and 10,000 to 30,000 EUR in Amsterdam once qualified eIDAS signatures with identity verification are required, for a timeline of 3 to 6 weeks. The real budget then depends on the per-signature cost, from 0.50 EUR for a simple signature to 5 EUR for a qualified one. For an agency network signing more than 300 contracts or mandates a month, a native integration pays for itself in under a year compared with paper or manual uploads to the provider's interface.

Which eIDAS level for which document

The EU eIDAS regulation defines three levels. The choice depends on the legal weight you need, not on technical convenience. A property management mandate does not require the same level of evidence as a business transfer deed.

In practice, 80% of an agency network's documents can use simple or advanced signatures. Reserving qualified signatures for cases where they are mandatory avoids tripling the bill. In the Netherlands, qualified flows often rely on a Dutch trust service provider and identity checks via passport NFC or iDIN, which explains the higher integration range.

What the API integration costs by provider

Yousign, Docusign (widespread in corporate groups) and Universign or Dutch qualified providers all offer APIs. Development cost depends mainly on the number of document templates, pre-filling and the internal approval workflow.

Watch out: some API plans charge a monthly minimum even when volume drops in summer. Negotiate a smoothed annual commitment rather than a monthly floor.

The technical choices that move the bill

Three decisions weigh most on the budget. First, where the document lives: generated by your application and sent to the provider, or built inside the provider's tool. The first option keeps control of templates and costs 2,000 to 3,000 EUR more upfront. Second, embedded signing (an iframe inside your app) versus email: embedded signing raises in-branch completion rates by 15 to 25% according to market feedback, but needs extra interface work. Third, evidential archiving: the evidence file must be kept 5 to 10 years depending on the act, either at the provider or in your own encrypted storage.

If your application is old or has no proper API, the integration may require a small rework of the contracts module. Plan a 3 to 5 day scoping phase before any firm quote.

Mini case study

Thomas, CIO of a 14-branch real estate network, handles 420 mandates and leases a month. Today each document is printed, signed, scanned and filed: 25 minutes of handling per file, or 175 hours a month. At a loaded cost of 32 EUR an hour, the paper process costs about 5,600 EUR a month, plus 900 EUR in registered mail and printing.

He budgets a full integration at 12,000 EUR and a 450 EUR monthly subscription. The 420 advanced signatures at 2.50 EUR add 1,050 EUR a month. Handling time drops to 5 minutes per file (35 hours, or 1,120 EUR). New monthly cost: 2,620 EUR versus 6,500 EUR. Savings: 3,880 EUR a month, payback in just over 3 months. If he later adds qualified signatures for 10% of files at 4.50 EUR, the extra cost is under 200 EUR a month.

FAQ

Does a simple electronic signature have legal value in the EU?

Yes, eIDAS states that an electronic signature cannot be denied legal effect simply because it is electronic. In a dispute, the evidence file is what matters, which is why a certified provider is important. At 0.50 to 1.50 EUR, it covers most commercial contracts.

Should we pick Yousign, Docusign or a Dutch qualified provider?

Yousign is often the simplest to integrate for a European SME, with clear documentation and pricing. Docusign makes sense when your clients or group already use it. A Dutch or EU qualified provider is the right call if more than 20% of your acts require qualified signatures.

How long does it take to add e-signature to an existing app?

Allow 3 weeks for a simple integration with two or three templates, and 6 weeks for a full multi-signer flow with archiving. An application without a proper API can add 2 to 3 weeks of preliminary work.

What happens if we switch signature provider?

If the integration isolates the provider behind an abstraction layer, switching costs 2,000 to 4,000 EUR instead of a rewrite. Evidence files already issued remain valid and should be exported before termination.

Is e-signature GDPR compliant?

Yes, provided the provider hosts data in the European Union and signers are informed. ID documents collected for advanced signatures need a defined retention period, often aligned with the contract's.

Let's scope your project. We scope your e-signature integration (document templates, eIDAS level, archiving) with an indicative budget and a 3 to 6 week timeline. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.