Retarus Fax Review 2026: Pricing, Certifications, and How It Compares

Is Retarus Cloud Fax Worth It in 2026?

A Cloud Veteran With a Traditional Sales Motion

Retarus was founded in Munich in 1992 by Martin Hager, who remains CEO, and has stayed privately owned without outside investor funding. It began by linking the Lotus cc:Mail LAN email system to CompuServe, then added hosted fax and email security services in the early 1990s, long before "cloud fax" existed as a category. In December 2024, IDC named Retarus a Leader in its MarketScape: Worldwide Digital Fax Vendor Assessment.

That history is Retarus's structural difference from a vendor like OpenText: there is no legacy on-premises server product in the portfolio to maintain or retire. A Retarus buyer evaluates one cloud product line, not a split between a server and a separate SaaS.

The Pitch and the Problem

The pitch: three decades of hosted fax experience, an audited compliance framework spanning healthcare, automotive, and financial-services requirements, deep SAP and Epic integration work, and a modern developer toolkit. The problem is what stands between a buyer and the product: no published price, and no self-serve way to test it before engaging sales. For a large, fully scoped deployment that tradeoff is reasonable, and Retarus's dedicated project-manager model is genuinely part of what enterprises are paying for. For a team that wants to evaluate, budget, and start quickly, it is friction.

When to Look Elsewhere

Organizations that want to evaluate and start faxing without a sales cycle have several modern cloud options. Documo is a dedicated cloud fax product with published pricing. RingCentral fits teams that want fax bundled into a phone system they are already buying. Fax.Plus is a modern cloud fax platform with published pricing, self-service administration, and native apps. Retarus still makes the most sense where the requirement itself is a fully scoped, IT-led implementation with negotiated terms.

About Retarus

Retarus GmbH is headquartered in Munich, Germany, with a US headquarters in Secaucus, New Jersey, and offices across roughly 30 countries. Martin Hager founded the company on December 2, 1992 and still serves as CEO, and Retarus has been privately owned since founding. The fax business grew out of the company's earliest hosted messaging services, and the current portfolio spans Cloud Fax, Transactional Email, Email Security, Enterprise SMS, EDI, E-Invoicing, and a separate Intelligent Document Processing line.

Getting a Price From Retarus

Retarus lists no price anywhere public for Cloud Fax. Getting one means starting a sales conversation, typically through a demo request. Here is what the process looks like based on public materials, so you know what to expect before you start it.

What Retarus Publishes Without a Quote

Retarus is consistent across its own site and third-party catalogs in describing the model without stating a figure: pricing is pay-per-use, based on batches and pages, tailored to each customer's volume, integrations, and compliance requirements. No reseller marketplace listing with even a visible pricing structure was found, and the speculative monthly figures on a few aggregator sites do not match Retarus's own materials and should not be trusted. A quote will typically also reflect implementation scope, since a dedicated project manager and migration team accompany customers from scoping through production, and that professional-services layer is part of what is being priced.

What the Self-Service Alternatives Publish, for Context

Unlike the self-service alternatives in the table below, Retarus publishes neither an entry price nor a page allowance. These are published entry points, not like-for-like enterprise quotes.

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For enterprise buyers, the practical difference is not the number itself but what can be done with it: a published entry point lets a team budget, test, and compare per-page value before anyone talks to sales, then negotiate volume terms from an informed position.

Beveiliging en naleving

The Certifications in Plain Language

• SOC 1 Type II and SOC 2 Type II: independent audit reports confirming that internal controls operate effectively over time, not just on paper. Retarus describes its SOC 2 Type II reporting as covering the design and operating effectiveness of its internal control system and ISMS.
• ISO/IEC 27001: the international information security management standard.
• HITRUST e1: a foundational healthcare security certification and a trust shortcut for hospital procurement; Retarus applies it specifically to its fax backend.
• TISAX: an automotive-industry information security standard built on ISO/IEC 27001; Retarus was certified by TÜV SÜD in 2020.
• HIPAA and BAA: the US patient-data law, and the signed contract that makes a vendor legally accountable for protecting that data.
• TX-RAMP: a Texas state government cloud security framework.

What Retarus Documents

Per Retarus's compliance page and Cloud Fax product pages, the company documents:

• SOC 1 Type II and SOC 2 Type II reporting, ISO/IEC 27001, HITRUST e1, TISAX, and TX-RAMP
• An ENS (high) certification in Spain (Esquema Nacional de Seguridad, the Spanish government's national security framework for public and regulated systems)
• Product-level compliance support for HIPAA, GDPR, NIST, FERPA, and CCPA
• References to newer European frameworks: DORA, NIS2, and KRITIS

Encryption is described as AES 256-bit and TLS, with PGP and X.509 available depending on transport.

Retarus names TÜV SÜD as the auditor behind its TISAX certification, but its public pages do not name the specific auditor or certification body for its SOC or ISO/IEC 27001 reporting. For comparison, Fax.Plus names EY CertifyPoint as both the auditor for its SOC 2 Type II report and the certification body for its ISO/IEC 27001 certification.

HIPAA en de BAA

Retarus states its products are designed to support customers' HIPAA compliance requirements, with customer data protected under contractual provisions covered by a BAA. As with any vendor, the exact scope of the BAA and which delivery methods it covers belongs in writing before contracts are signed.

Receiving a fax through ordinary email is not automatically HIPAA compliant. Compliance depends on the vendor's BAA coverage, transmission security, access controls, account configuration, and how the receiving organization handles PHI, not on any single technical property. Retarus offers Fax-to-Email with dedicated Exchange and Microsoft 365 integrations; how PHI-safe delivery is configured there is an implementation question to settle during scoping. Fax.Plus documents this workflow as a product: HIPAA-compliant Fax-to-Email on Enterprise lets healthcare teams receive faxes through existing email workflows under a signed BAA, using a dedicated TLS-enforced address, with standard email-to-fax explicitly labeled for non-PHI use.

Apps and Access

Retarus Cloud Fax is accessed through WebExpress, a browser-based portal for sending, receiving, and managing faxes, and the Enterprise Fax Portal and EAS administration layer for team faxboxes, folders, permissions, reporting, and live transmission monitoring, with two-factor authentication and SSO. Desktop faxing runs through Faxolution for Windows, including Word mail-merge broadcasting. Email faxing covers Exchange, Microsoft 365 (with an Outlook add-in on Microsoft AppSource), and HCL Notes Domino, with Active Directory synchronization. MFP and output-management integration comes both directly and through PaperCut, LRS, and ActFax.

There is no native Retarus iOS or Android app. Retarus's own healthcare materials describe extending fax "to MFDs and mobile apps via output management," meaning a partner's app with a Retarus integration; mobile access on Retarus itself runs through the browser portal or email.

How Access Compares

Fax.Plus pairs its enterprise administration (multi-admin, SSO, user permissions, analytics) with native iOS and Android apps, Windows and macOS desktop apps, a web app, email-to-fax, and Google Workspace, Microsoft, Slack, and Zapier integrations, all reachable from self-serve signup. Documo connects existing fax hardware into its cloud platform, and RingCentral's fax lives inside its phone-system apps. Retarus's portal and admin tooling are deep for IT-led deployments; the gap is end-user reach beyond the desk.

Support, Contracts, and Onboarding

Retarus publicly claims 99.99% uptime across its global infrastructure and adaptable SLAs for critical business processes, but it does not publish a standard SLA document or contractual service-credit structure. Its public terms list the SLA among the separately agreed contract documents, so the actual availability commitment a customer gets is set per agreement. The support model is a real differentiator in Retarus's own marketing: a 95% first-call resolution rate, experienced technicians rather than call centers or chatbots, and a dedicated project manager from scoping through production. Independent corroboration is limited either way, since Cloud Fax has few public customer reviews.

What Retarus does publish is its General and Special Terms and Conditions, as per-country PDFs on its site, and they are worth reading before a quote conversation. The US terms (version 06/2023) contain several concrete mechanics a buyer should know going in: during the minimum term, an agreement can be terminated for cause only, unless a trial period has been expressly agreed; after the first twelve months, Retarus may raise prices annually in line with the US employment cost index, capped at 7.5% per year, with 30 days' notice; invoices are deemed accepted if not disputed in writing within 8 weeks; and the services are provided as is, with no warranty that they will be uninterrupted, error free, or that any message will be successfully delivered, and liability capped at the greater of twelve months of fees or $10,000. On the constructive side, the same terms commit Retarus to cooperate with written requests to port fax numbers to another provider at termination or expiration.

Gegevensopslag en -bewaring

Retarus currently describes its Cloud Fax infrastructure as operating across six data centers in the United States, Europe, and Singapore, with redundant network infrastructure and carriers; its public fax API documentation exposes regional endpoints for Germany, the US, Switzerland, and Singapore, including high-availability variants. Regional processing is arranged with Retarus during scoping, rather than switched by the customer in a dashboard.

Retention on Retarus is configurable rather than a single fixed default: fax job data is deleted automatically after a configured retention period, API status reports are retrievable for up to 30 days or until deleted, GraphQL reporting supports a 90-day lookback, and optional archiving can copy sent and received faxes into the customer's own storage, including S3 buckets from the Enterprise Fax Portal.

How Residency Compares

On Fax.Plus, US customer data stays in the US by default, and residency is an account-level Enterprise setting: admins choose among more than 20 storage locations across North America, Europe, and Asia-Pacific and can migrate encrypted documents between regions from the dashboard, per Alohi's data residency documentation. Retarus's regional footprint is smaller and configured through the vendor.

Enterprise, API-automatisering en automatisering in de gezondheidszorg

The API and Developer Experience

Retarus's developer story is stronger and more open than its sales-led buying process suggests. Fax-for-Applications is available via REST (JSON) and SOAP interfaces, documented publicly at developers.retarus.com with mock servers, and test accounts are available on request. Inbound delivery paths include Fax-to-Webservice push, Fax-to-FTP and SFTP, a polling API, and HTTP status-push notifications for outbound jobs. Retarus publishes open-source SDKs for Java, Python, Node.js, and Rust through GitHub and the relevant language-specific package registries, plus a public integration package for SAP BTP and the SAP Integration Suite. A GraphQL Reporting API provides automated access to usage and delivery data across fax, SMS, and email, and observability metrics stream in the Prometheus data model for real-time monitoring in the customer's own tooling.

Real-Time Monitoring and Fax Streaming

Retarus publicly documents real-time transmission monitoring and reporting: administrators get live insight into faxes while they are in transmission, and the reporting APIs return delivery status and metrics. Its public materials do not clearly explain whether incoming fax content can be delivered incrementally, page by page, before the transmission is complete. Fax.Plus publicly documents Fax Streaming as a defined enterprise workflow for exactly that: delivering incoming fax pages while transmission is still underway, so downstream systems can start processing before the full document lands.

Healthcare and EHR Connectivity

Retarus documents its Epic connector in the greatest depth, including a listing in Epic's connection hub, status updates pushed back into the Epic instance, and a major healthcare case study in Beth Israel Lahey Health, while its broader healthcare materials also position Cloud Fax for Cerner and other EHR environments. Fax.Plus Enterprise documents EHR connectivity across Epic, Cerner, athenahealth, NextGen, and Kipu EMR alongside its HIPAA Fax-to-Email workflow.

AI: Retarus IDP and Alohi AI

Retarus offers a genuine Intelligent Document Processing product: OCR plus machine-learning and LLM-based extraction, human-in-the-loop correction, and integrations into SAP S/4HANA, Oracle Order Management, Microsoft Dynamics 365, and Salesforce. But IDP is positioned as a separate Business Process Solutions product, not an included Cloud Fax feature.

Alohi AI takes the opposite packaging approach: AI Data Extraction and AI Text Transcript are integrated into the Fax.Plus fax experience itself, run from the document viewer or automatically on inbound faxes, with structured key-value output ready for export into EHR, CRM, and billing workflows, HIPAA-compliant processing, and 1,000 monthly AI Credits included on Enterprise.

MCP: Documentation Access and Operational Fax Actions

Both offerings support developers working with MCP, but they solve different problems. Retarus exposes its API documentation through a read-only Docs MCP Server, launched in May 2026 at developers.retarus.com, giving AI coding tools such as Claude, Cursor, and VS Code read-only access to Retarus API documentation. By Retarus's own description it does not make API calls on the user's behalf, send or receive faxes, or access customer data or fax activity.

The Fax.Plus MCP also provides a developer-focused MCP server for accessing and working with its API documentation. In addition, it offers a hosted operational endpoint at mcp.fax.plus that exposes more than 40 authorized, scoped tools to AI applications and agents. These tools can carry out real fax operations, including sending faxes, retrieving received faxes, tracking delivery status, managing contacts, listing fax numbers, and configuring webhooks.

In other words, both platforms help AI coding tools understand their API documentation, but Fax.Plus goes a step further by allowing authorized AI applications and agents to interact with real fax workflows.

Alternatives to Retarus

Fax.Plus: Best overall enterprise alternative

Fax.Plus is the stronger overall alternative for organizations that want enterprise fax automation without giving up pricing transparency, native apps, modern administration, or integrated AI workflows. Enterprise, published at $99.99 per month (or $79.99 per month billed annually) with unlimited users, supports HIPAA Fax-to-Email under a signed BAA, EHR connectivity, publicly documented Fax Streaming, Alohi AI with automated AI Data Extraction, a public REST API with SDKs, an operational MCP endpoint for AI agents, and data residency across more than 20 regions, with ISO/IEC 27001 certified by EY CertifyPoint and SOC 2 Type II independently audited through EY CertifyPoint, and a free tier to evaluate before anyone talks to sales.

Best for: Organizations that want Retarus-class compliance and automation with published pricing, self-service administration, and a shorter path from evaluation to production.

Documo: Certification-heavy, with an annual-only entry plan

A dedicated cloud fax product with HITRUST, ISO 27001, SOC 2 Type II, and PCI DSS certifications, HIPAA with a BAA, and document automation on upper tiers. The entry Solo plan is annual-billing only, a $300 up-front commitment, and there is no Android app.

Best for: Teams that want a dedicated, compliance-heavy cloud fax product with published pricing.

RingCentral: Fax inside a full phone system

A UCaaS vendor selling fax as a standalone plan or bundled into its phone system at published per-user rates, on multi-year telecom contracts with auto-renewal.

Best for: Teams that want faxing inside a business phone system they were buying anyway.