Terms of Service

By accessing and using Sello Sign ("the Service"), operated by Proxima AI LLC ("Proxima", "we", "our", "us"), you agree to be bound by these Terms of Service. If you disagree with any part of these terms, you may not access the Service.

These terms apply exclusively to the use of the cloud service hosted by Proxima (sign.sello.page). If you use Sello Sign in self-hosted mode, the software is governed solely by the AGPL-3.0 license and these Terms of Service do not apply to you.

These terms apply to all users of the cloud platform, including electronic invoicing providers and members of their organizations.

Sello Sign is an electronic signing platform designed for electronic invoicing providers. The Service enables digital signing of tax documents for fiscal compliance in Central America and the Caribbean, including FE (Factura Electrónica) in Costa Rica and Panama, e-CF (Comprobante Fiscal Electrónico) in the Dominican Republic, and DTE (Documento Tributario Electrónico) in El Salvador and Guatemala.

The Service currently operates in five jurisdictions: Costa Rica (Ministerio de Hacienda, Dirección General de Tributación), the Dominican Republic (Dirección General de Impuestos Internos), El Salvador (Ministerio de Hacienda), Guatemala (Superintendencia de Administración Tributaria, FEL regime) and Panama (Dirección General de Ingresos of the Ministry of Economy and Finance, where validation is performed by an authorised Proveedor Autorizado Calificado). We may progressively enable additional jurisdictions, including Ecuador, Bolivia, Peru, Colombia, Uruguay and Brazil; until they are enabled they are shown as "coming soon" and cannot be used.

• 01 Management of issuers (taxpayers) and their signing certificates
• 02 Digital signing of electronic tax documents
• 03 API for integration with invoicing systems
• 04 Secure storage of signing certificates
• 05 Public digital signature verification tool (client-side processing)

You are responsible for maintaining the confidentiality of your account and password. You must notify us immediately of any unauthorized use of your account.

Each workspace represents an organization (invoicing provider). Member roles (owner, admin, member) determine permissions within the workspace.

Paid plans are billed on a subscription basis, monthly or yearly, at the prices published on the pricing page. Subscriptions renew automatically at the end of each period unless cancelled beforehand. On paid plans, production signatures beyond the included monthly quota are billed as overage at the published rate.

Card payments are processed through a third-party payment processor that may act as the merchant of record for the transaction. In that case, your purchase is made from that processor, which issues the payment receipt, handles the indirect taxes applicable to the sale, and whose terms govern payment processing. When the processor does not act as merchant of record or Proxima invoices you directly, Proxima is the seller of the transaction.

Unless expressly stated otherwise, published prices do not include taxes, fees, duties, or withholdings of any jurisdiction. You are responsible for the taxes that apply to you for the use of the Service in your country, including value-added or sales taxes where applicable.

For accounts with direct invoicing (enterprise plans or negotiated agreements), payments must be made in the full agreed amount, without deductions. If applicable law requires a withholding on the payment, the amount payable shall be increased as necessary so that Proxima receives the full agreed amount, unless the written agreement between the parties provides otherwise. In case of conflict, that agreement prevails.

The Service is provided as a license to use standard software on a subscription basis (software as a service). It does not constitute custom software development, consulting, technical assistance, or professional services. This classification applies for contractual and tax purposes, unless a specific enterprise agreement provides otherwise.

Refunds: subscriptions are billed in advance and are not refundable on a pro-rata basis upon cancellation; you keep access to the plan until the end of the period already paid for. We evaluate refunds for failures attributable to the Service or duplicate charges case by case, within 30 days of the charge.

Price changes: we may modify published prices. Any increase applicable to your subscription will be notified by email at least 30 days in advance and takes effect on your next billing period. If you disagree, you may cancel before that date.

You agree to use the Service in accordance with applicable law and these Terms. In particular, you may not:

Breach of this section may result in suspension of access under the Termination section.

• 01 Sign documents with certificates you are not authorized by their holder to use
• 02 Use the Service to issue fraudulent documents or simulate non-existent transactions
• 03 Attempt to access data, workspaces, or issuers that do not belong to you
• 04 Run load, scanning, or intrusion testing without prior written authorization
• 05 Resell or sublicense access to the Service outside your relationship with your own taxpayers
• 06 Use the Service from jurisdictions subject to sanctions that prohibit it

API keys are secret and must not be shared or exposed in client-side code. You are responsible for all activities performed with your API keys.

We reserve the right to limit or suspend API access if we detect abusive, excessive, or destabilizing usage of the Service.

Signing certificates you upload to the platform are stored in encrypted form. You are responsible for the validity and currency of the certificates you use.

Sello Sign acts as a signing tool and is not responsible for the legal validity of signed documents before the corresponding tax authorities: Ministerio de Hacienda in Costa Rica and El Salvador, DGII in the Dominican Republic, SAT in Guatemala, and Dirección General de Ingresos (DGI) of the Ministry of Economy and Finance in Panama. It is the user's responsibility to ensure documents comply with the tax regulations applicable in each jurisdiction.

The public signature verification tool operates exclusively in the user's browser. Certificates loaded in this tool are not transmitted to our servers nor stored at any time. All cryptographic processing is performed locally using the browser's Web Crypto API.

Authority over issuer data: you represent and warrant that you have sufficient authorization from each issuer (taxpayer) to upload and process their certificates and tax data through the Service, and that you have met the disclosure and consent obligations owed to them. You are responsible for that relationship; Proxima acts as data processor on your behalf.

Guatemala (FEL regime): Sello Sign applies only the taxpayer's emission signature (XAdES-BES over the DatosEmision node). Sello Sign is not a SAT-authorised Certificador, does not apply the certification signature and does not manage the authorisation number. Acceptance of the document depends on the Certificador you contract and on SAT; Proxima is not liable for its rejection. For that reason Guatemala is offered in beta.

The handling of your personal data and your issuers' data is governed by our Privacy Policy. By using the Service, you consent to the collection and use of information as described in that policy.

Sello Sign is open source software licensed under the GNU Affero General Public License v3.0 (AGPL-3.0). The source code is available in the official repository. Any modifications distributed or used as a service must be published under the same license.

In the event of a conflict between these Terms of Service and the AGPL-3.0 license, the AGPL-3.0 license prevails in all matters relating to source code rights (use, modification, distribution). These Terms exclusively govern the service relationship between you and Proxima when using the cloud platform.

The names "Sello Sign" and "Proxima", as well as associated logos, are trademarks of Proxima AI LLC and are not covered by the open source license. Forks and modified versions must use a different name and branding. See our trademark policy for details.

The data, certificates, and documents you process through the Service remain your property. We do not claim rights over the content you process.

The Service is provided "as is" and "as available". We do not guarantee that the Service will be uninterrupted, secure, or error-free.

In no event shall we be liable for any indirect, incidental, special, or consequential damages resulting from the use or inability to use the Service, including but not limited to loss of data, loss of revenue, or business interruption.

In any event, Proxima's total and aggregate liability for any claim arising from these Terms or from the use of the Service is limited to the amount you paid Proxima for the Service during the twelve (12) months preceding the event giving rise to the claim, or one hundred US dollars (USD 100), whichever is greater.

The limitations above do not apply in cases of willful misconduct, fraud, or gross negligence, nor to liabilities that applicable law does not permit to be excluded or limited.

Indemnification: you will hold Proxima harmless against third-party claims arising from your use of the Service in violation of these Terms, in particular from uploading or using certificates without the holder's authorization, from the content of the documents you sign, and from breaching your tax or data protection obligations toward your issuers.

We recognize that our customers are electronic invoicing providers whose taxpayers depend on continuity of the signing service. Termination therefore follows a staged and reversible process.

Termination by the user: you may request deletion of your workspace at any time from settings. For 30 days after the request the workspace enters a grace period: the signing API remains operational so your taxpayers' invoicing is not interrupted, you can export your data and certificates, and you can cancel the deletion and keep the workspace.

Once the grace period elapses, termination becomes effective: the signing API stops responding, but your data is retained for a further 90 days, during which you can still export it or request restoration of the workspace.

After those 120 days from the request, the workspace data — issuers, certificates, API keys, and signing records — is permanently and irreversibly deleted.

Termination for breach: in case of violation of these Terms, we will notify you by email and grant a 15-day period to remedy the situation before suspending access. During that period the signing service continues to operate normally.

Immediate termination: we reserve the right to suspend access immediately, without prior notice, only in serious cases that endanger the security of the platform or of third parties, such as fraudulent use of the service, credential compromise affecting other users, or activities that violate the law.

We may modify these Terms. Material changes — in particular those relating to pricing, billing, limitation of liability, or termination — will be notified by email at least 30 days before they take effect.

Non-material changes, such as wording corrections or clarifications, take effect upon posting on this page. Continued use of the Service after the effective date constitutes your acceptance of the modified terms.

Entire agreement: these Terms, together with the Privacy Policy and any enterprise agreement executed in writing, constitute the complete agreement between you and Proxima regarding the Service, and supersede any prior communication on the same subject.

Severability: if any provision of these Terms is held invalid or unenforceable, the remainder stays in full force and that provision will be construed as closely as possible to its original intent.

Waiver: Proxima's failure to exercise a right under these Terms does not constitute a waiver of the right to exercise it later.

Assignment: you may not assign these Terms without our prior written consent. Proxima may assign them to an affiliate or in connection with a merger, acquisition, or sale of assets, notifying you through the Service.

Force majeure: neither party is liable for failure to perform its obligations when caused by circumstances beyond its reasonable control, including natural disasters, armed conflict, widespread internet infrastructure failures, or acts of authority. This clause does not excuse payment of amounts already accrued.

These Terms of Service are governed by and construed in accordance with the laws of the State of Wyoming, United States of America, without giving effect to its conflict-of-law rules.

Any claim brought against Proxima shall be subject to the exclusive jurisdiction of the state and federal courts located in the State of Wyoming, and you waive any objection based on inconvenient forum. Proxima may additionally bring actions in any competent jurisdiction where you are domiciled or hold assets, including actions for the collection of amounts due.

Nothing in this section prevents Proxima from seeking injunctive, precautionary, or urgent relief before any competent court to protect its intellectual property rights, the security of the platform, or compliance with the AGPL-3.0 license, without first resorting to the courts of Wyoming.

Written negotiated enterprise agreements may provide for a different governing law or dispute-resolution mechanism, including arbitration. In case of conflict, the provisions of that agreement prevail.

These Terms are published in Spanish and English. In case of discrepancy between the two versions, the English version prevails and is binding for purposes of legal interpretation. The Spanish version is provided for ease of understanding.

If you have questions about these Terms of Service, you can contact us at

legal@proxima.la