Question 1

What is Scell.io?

Accepted Answer

Scell.io is a unified B2B API for issuing compliant electronic invoices (Factur-X, UBL, CII) and collecting simple electronic signatures (SES) compliant with the European eIDAS regulation. It targets software publishers, integrators and businesses that want to automate these workflows without building a regulatory infrastructure in-house.

Question 2

Is Scell.io a PDP or a dematerialisation operator?

Accepted Answer

Scell.io is a dematerialisation operator (OD). We are not a PDP. As an OD, you can generate compliant electronic invoices in all required formats (Factur-X, UBL, CII) and transmit them through our partner SuperPDP.

Question 3

How does the credit-based model work?

Accepted Answer

No subscription. Scell.io runs on prepaid credits. You purchase a credit pack (starting at €50) and each operation consumes credits: €0.04 per invoice issued, €1.20 per signer (not per document — a document sent to 3 signers costs 3 × €1.20 = €3.60). Credits are valid for 12 months. No hidden fees, no commitment.

Question 4

Is there a sandbox environment for testing?

Accepted Answer

Yes. Every account has an isolated sandbox environment, accessible via keys prefixed with sk_test_*. Sandbox calls do not consume credits and do not produce any legally valid document. You can switch between production and sandbox from the dashboard or via the X-API-Key header of your requests.

Question 5

Which electronic invoicing formats are supported?

Accepted Answer

Scell.io generates invoices compliant with European standards: Factur-X (Minimum, Basic WL, Basic, EN 16931, and Extended profiles), UBL 2.1, and CII (Cross Industry Invoice). These formats cover the requirements of the French 2026 reform and the EN 16931 standard. The format can be selected per API call based on your recipient's needs.

Question 6

How does invoice numbering work?

Accepted Answer

Numbering is fully automatic and managed by Scell.io. Each invoice receives an internal identifier in the format DRAFT-XXXXX upon creation, then a definitive sequential number in the format XXXXX-YYYYMM-NNNNN upon issuance (where XXXXX is your tenant identifier, YYYYMM the year and month, and NNNNN the rank in the sequence). This unbroken chronological numbering complies with French tax obligations.

Question 7

What is the Reliable Audit Trail (PAF)?

Accepted Answer

The Reliable Audit Trail (PAF) is the set of documentary elements that justify the chain between a purchase order, a delivery note, and an invoice. Scell.io automatically stores the required metadata (order references, dates, party identifiers) and associates them with each issued invoice to satisfy the requirements of Article 289 of the French General Tax Code during a tax audit.

Question 8

What does the 2026 e-invoicing reform mean for my clients?

Accepted Answer

From September 2026 (large companies and mid-sized businesses) and then 2027 (SMEs, micro-businesses), all French B2B transactions must be issued and received in structured electronic format via a PDP or the PPF. Scell.io prepares your clients today: the invoices generated already comply with the technical specifications and workflows expected by the future public invoicing portal.

Question 9

What level of electronic signature does Scell.io offer?

Accepted Answer

Scell.io implements the Simple Electronic Signature (SES) as defined by the eIDAS regulation (EU 910/2014). This level is suited to standard commercial contracts, quotes, terms and conditions, and internal documents. We do not offer Advanced (AES) or Qualified (QES) signatures: if your use case requires a higher level, contact us to evaluate the available options.

Question 10

How does SMS OTP verification work?

Accepted Answer

During a signing workflow, a 6-digit one-time code (OTP) is sent by SMS to the signer's phone number. It must be entered within 10 minutes to validate the signing act. This mechanism provides an additional timestamped identity proof, integrated into the document's audit log. SMS delivery is handled directly by our signature provider OpenAPI.com and is included in the per-signer cost (€1.20 per signer, not per document).

Question 11

Can multiple signers be managed on the same document?

Accepted Answer

Yes. The API accepts an array of signers per signature request. You can define a sequential order (each signer is notified after the previous one has validated) or a parallel mode (all signers are contacted simultaneously). The document is only considered fully signed once all parties have validated.

Question 12

What is the legal value of the signatures produced?

Accepted Answer

eIDAS SES signatures carry evidentiary value recognised before European courts. Each signature comes with a comprehensive audit log: signer identity, certified timestamp, IP address, recorded consent, validated SMS OTP. This evidence file is exportable as a PDF from your dashboard and serves as the supporting document in the event of a dispute.

Question 13

Which official SDKs are available?

Accepted Answer

Scell.io publishes three official SDKs: a TypeScript/JavaScript SDK (compatible with Node.js, Deno, and the browser), a PHP SDK (compatible with Laravel, Symfony, and native PHP), and an MCP (Model Context Protocol) server that allows AI agents such as Claude to call the API directly from automation workflows. All are available on npm and Packagist.

Question 14

What are the 4 supported authentication modes?

Accepted Answer

The Scell.io API supports four modes depending on the usage context: (1) Sanctum SPA via HttpOnly cookies for the scell.io dashboard, (2) secret key sk_* via the X-API-Key header for server-to-server calls (invoices, signatures, webhooks), (3) publishable key pk_* via X-Publishable-Key for client-side JavaScript widgets of partner tenants, (4) tenant key via X-Tenant-Key for multi-tenant endpoints (legacy mode).

Question 15

How do webhooks work?

Accepted Answer

Scell.io sends webhooks via HTTP POST to notify your system of key events: invoice issued, signature completed, OTP expired, payment received, etc. Each request is signed with a shared secret via HMAC-SHA256 (X-Scell-Signature header). You can configure multiple destination URLs, filter by event type, and manually replay a webhook from the dashboard.

Question 16

Where is data hosted?

Accepted Answer

All Scell.io data is hosted in France on Scaleway infrastructure (Paris zones). The PostgreSQL database, invoice files and signed documents (S3 object storage), and Redis message queues reside exclusively on servers located within the European Union. No data transfers to third countries are made.

Question 17

Is Scell.io GDPR compliant?

Accepted Answer

Yes. Scell.io acts as a data processor within the meaning of Article 28 of the GDPR for the personal data you transmit to it. A DPA (Data Processing Agreement) is available and can be signed from your client portal. Data is processed according to the minimisation principle, a processing register is kept up to date, and you have the right to data portability and erasure.

Question 18

How long are invoices archived?

Accepted Answer

Issued invoices are archived for 10 years in accordance with Article L123-22 of the French Commercial Code. Archiving is performed on immutable object storage with SHA-256 integrity logging and RFC 3161 TSA anchoring. You can export all your invoices at any time in PDF/A format or as raw JSON data from the API or the dashboard.

Question 19

Who are your technical sub-processors?

Accepted Answer

Scell.io uses the following providers, all subject to GDPR-compliant DPAs: Scaleway (hosting and storage, France, ISO 27001/HDS certified), SuperPDP (Factur-X/UBL/CII generation engine, EU), OpenAPI.com (eIDAS signature infrastructure and SMS OTP delivery, EU). The complete and up-to-date list is available in our privacy policy.

Frequently asked questions

General

Electronic invoicing

Electronic signatures

Technical integration

Data & compliance

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