The verdict in three sentences
SaaS vendors (DocuSign, Yousign) are perfect up to a few thousand signatures, but their per-envelope cost becomes punishing at volume and you never own the validation workflows. A custom platform integrated into your processes (workflows, vault, eIDAS legal value) is built for 25,000 to 60,000 EUR net over 10 to 18 weeks. The economic tipping point sits around 5,000 signatures/year.
Per-envelope cost vs custom platform
The SaaS model is linear: the more you sign, the more you pay. Custom is a fixed investment amortized over volume. 2026 order of magnitude.
| Annual volume | DocuSign/Yousign (per envelope) | Custom platform (amortized 3 yrs) |
|---|---|---|
| 1,000 signatures | ~1,200 EUR net/yr | not worth it |
| 5,000 signatures | ~5,500 EUR net/yr | ~13,000 EUR net/yr equivalent |
| 15,000 signatures | ~15,000 EUR net/yr | ~14,000 EUR net/yr |
| 50,000 signatures | ~45,000 EUR net/yr | ~16,000 EUR net/yr |
| Marginal cost / signature | 0.50-2 EUR net | ~0.02 EUR net (timestamp) |
| Workflow ownership | No | Yes |
Below 5,000 signatures/yr, stay with a vendor. Beyond that, each extra envelope costs almost nothing in custom, while it stays full-price at the vendor.
eIDAS compliance and legal-value archiving
A legal signature must withstand a court challenge. The eIDAS level determines the burden of proof.
| eIDAS level | Typical use | Technical requirement |
|---|---|---|
| Simple (SES) | Internal docs, HR | Consent + trace |
| Advanced (AES) | Commercial contracts | Strong ID, signatory link |
| Qualified (QES) | High-stakes deeds | Qualified certificate, trust provider |
| Qualified timestamp | Date proof | RFC 3161 token |
| Vault NF Z42-020 | Legal archiving | Sealing, integrity, log |
A custom platform delegates the qualified part to a certified trust service provider (via API), while keeping the workflows, vault and audit trail with you.
Validation workflows built into your processes
This is the real difference: signing is not a silo, it lives inside your business.
| Function | Standard SaaS | Custom platform |
|---|---|---|
| Multi-validator circuit | Basic | Unlimited business rules |
| Automatic trigger | Limited | From CRM/ERP/DMS |
| Legal-value vault | Paid add-on | Built in |
| Smart reminders | Standard | Customized |
| Compliance reporting | CSV export | Real-time dashboard |
Mini case study
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Ms. Riviere, general counsel of a 900-employee services group in Lille, signs 22,000 documents/yr (contracts, amendments, mandates). At her vendor that is ~20,000 EUR net/yr and a bill that climbs with growth. She orders a custom platform at 48,000 EUR net, maintenance 8,000 EUR net/yr, integrated into her ERP. Smoothed over 3 years: ~24,000 EUR net/yr at first, then the marginal cost per signature drops to near zero. From year 2 she saves ~12,000 EUR/yr and gains automated validation circuits that remove 3 days of average delay per contract.
FAQ
At what volume is custom worthwhile?
Around 5,000 signatures/yr. Below that, a SaaS vendor stays cheaper. Above, the gap widens fast in your favor because the marginal cost becomes negligible.
Is qualified eIDAS signature possible in custom?
Yes, by relying on a qualified trust service provider via API. You keep the workflows and vault; the qualified certificate is delegated to the certified third party.
How long is the build?
Between 10 and 18 weeks depending on the number of circuits, integrations (CRM, ERP, DMS) and target eIDAS level. A first simple flow can ship in 6-8 weeks.
What about legal value in a dispute?
It rests on the qualified timestamp, the tamper-proof audit trail and legal-value archiving (NF Z42-020). These are admissible before a court.
Can we connect the platform to our business tool?
Yes, that is the main benefit: automatic triggering from your CRM, ERP or DMS, with no re-keying. Integrations represent 20 to 30 % of the budget.
Let's scope your project. Tell us your annual signature volume, your target eIDAS level and the tools to connect: we price a platform between 25,000 and 60,000 EUR net. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
