Ark vs Onthen

Native Multi-Tenant Architecture

Ark is built from the ground up for platforms with multiple customers. Every tenant is automatically isolated with their own domains, sending logs, analytics, and debugging data. This eliminates the need to build complex tenant isolation layers on top of a single-sender email API, providing immediate clarity and control per customer directly out of the box.

AI-First Developer Workflow

Ark integrates seamlessly into the modern AI-powered development stack. It features AI-readable documentation that reduces token usage by 10x and a native MCP server with 26 tools. This allows AI coding assistants like Claude, Cursor, and Windsurf to generate production-ready code and manage email operations through natural language, dramatically speeding up integration and feature development.

Automated Domain & DNS Management

Onboarding new customer domains is simplified to a two-minute process. Ark automatically detects the customer's DNS provider (e.g., Cloudflare, GoDaddy, Route53) and provides them with exact, step-by-step instructions. For some providers, it can configure DNS records automatically, removing the need for support calls to explain technical details like TXT records.

White-Label Email Infrastructure

Ark provides a complete white-label solution where every email sent appears authentically from your customer's domain (e.g., [email protected]). It handles all underlying authentication (SPF, DKIM, DMARC) and delivers robust infrastructure with sub-second delivery times and 99.9% deliverability, making your platform feel like an integrated part of your customer's business.

Branded Onboarding Pages

Create a completely white-labeled and frictionless onboarding experience. Simply upload your logo and select a primary color, and Onthen applies your branding across the entire participant task page and all automated communications. This presents a professional, cohesive image and builds trust from the very first interaction, removing the generic feel of standard tools.

Flexible Task Actions & Automation

Move beyond simple checklists with a powerful library of task actions. Combine built-in actions like secure document uploads, form fills, identity verification (KYC), and photo requests with third-party app integrations. Automate the busywork by setting up reusable templates and letting the system handle automatic nudges for overdue tasks, keeping processes moving without manual chasing.

Built-in Collaboration & Comments

Centralize all communication directly on the task page. Participants and your team can collaborate in one place using comments, ask questions, and provide updates. Participants can even delegate tasks to others within the same page. This transparency ensures everyone is aligned, reduces email clutter, and keeps tasks progressing smoothly.

CRM Synchronization & Dashboard

Onthen acts as a bridge to your existing systems. Every action, form submission, and file upload is automatically synced to your CRM's timeline and custom fields, making it the single source of truth. Monitor all ongoing onboardings from a customizable dashboard that gives you a real-time overview of statuses, pending tasks, and completions.

CRM & Helpdesk Platforms

CRM and helpdesk software needs to send notifications, ticket updates, and alerts from each client's own domain to maintain brand consistency and trust. Ark enables these platforms to offer fully white-labeled email communication without managing the technical complexity of domain authentication and logging for hundreds of separate customers.

Invoicing & Billing Tools

Financial tools require high-trust emails like invoices, payment receipts, and statements to come directly from the client's domain (e.g., [email protected]). Ark ensures these critical transactional emails are properly authenticated for maximum deliverability, providing a seamless, professional experience that reinforces the client's brand.

Scheduling & Booking Applications

Scheduling apps send confirmations, reminders, and calendar invites. With Ark, these emails originate from the business's domain (e.g., [email protected]), increasing open rates and reducing the chance of emails being marked as spam. The automated domain setup makes customer onboarding effortless.

Internal Tool Builders (using AI)

Developers using AI assistants like Cursor or Windsurf to build internal tools can use Ark to add email features (password resets, alerts) in minutes. The AI-native API and documentation allow developers to describe what they need in natural language and get production-ready code, bypassing the traditional learning curve of email APIs.

Client Onboarding for Service Businesses

Agencies, law firms, and consultancies can streamline how they collect client information, contracts, and initial project details. Replace back-and-forth emails with a branded page where clients complete forms, upload necessary files, and e-sign documents. All data flows directly into the CRM, ready for the team to start work immediately.

Financial Services & Compliance Checks

Fintechs, banks, and property managers can integrate KYC, proof of address, and identity verification directly into the onboarding workflow. Guide customers through secure, compliant checks on a single page, collecting all required documentation and audit trails automatically, significantly reducing manual review and fraud risk.

Employee & New Hire Onboarding

HR teams can provide a structured, welcoming first experience for new hires. Create a checklist that includes submitting personal details, signing policies, setting up IT accounts, and completing training modules. The centralized page ensures nothing is missed, and automatic reminders keep the process on schedule before day one.

Partner and Vendor Onboarding
Businesses that onboard suppliers, affiliates, or channel partners can standardize their process. Use Onthen to collect company information, tax forms, compliance certificates, and contract agreements through a unified portal. This ensures all partner data is collected consistently and stored securely in your central system.

Ark offers simple, transparent pay-per-email pricing that scales with your customer base. Plans start at $29 per month, which includes capacity for 10 customer domains and 50,000 emails. You can scale up to manage 1,000 domains or more as needed. Every plan includes unlimited team members, full access to the multi-tenant dashboard, automated DNS management, and all white-label features. A 7-day free trial is available with no credit card required to start.

Pricing information is not provided in the available content. For detailed information on plans, tiers, and costs, please visit the official Onthen website or contact their sales team directly.

Ark is the white-label email API purpose-built for modern SaaS platforms and multi-tenant applications. It is specifically designed for companies building products like CRMs, helpdesks, invoicing tools, or scheduling software that need to send email on behalf of their customers. Unlike traditional email services built for a single sender, Ark treats multi-tenancy as the default. It eliminates the immense complexity of managing hundreds of customer domains, SPF/DKIM/DMARC authentication, and per-tenant email logs. Developers integrate once and can then manage every customer domain from a single dashboard. Ark's core value is enabling teams to ship robust, white-labeled email functionality in minutes instead of spending weeks or months building and maintaining custom email infrastructure on top of generic APIs. It combines enterprise-grade deliverability with an intuitive, AI-native workflow, making it the essential tool for platforms that scale with their customer base.

Onthen is a centralized onboarding platform designed to eliminate the chaos of traditional client and employee onboarding. It replaces endless email chains, scattered documents, and manual follow-ups with a single, branded task page accessible via a unique link. The platform is built for businesses that need to onboard clients, new hires, or partners efficiently, including agencies, financial services, HR teams, and SaaS companies. Its core value proposition is frictionless collaboration: participants complete tasks without creating passwords, while internal teams gain full visibility and automated tracking. Onthen syncs all collected data and actions directly to your CRM, ensuring your customer records are always up-to-date. By providing clear to-do lists, automated reminders, and a unified workspace, Onthen ensures every onboarding process stays on track, reduces administrative overhead, and delivers a professional, seamless first impression.

How is Ark different from Resend or SendGrid?

Ark is purpose-built for multi-tenant platforms, while services like Resend, Postmark, or SendGrid are designed for a single company to send from its own domains. With Ark, multi-tenancy, per-customer domain management, and isolated logs are built-in defaults, not features you have to engineer on top of their API.

What does "AI-first" or "AI-native" mean for an email API?

It means Ark's documentation and tooling are optimized for AI coding assistants. The documentation is structured to be easily understood by AI models, reducing token usage. More importantly, Ark provides a Model Context Protocol (MCP) server, allowing AI agents to directly use its 26 tools to write code and manage email operations through conversation.

How difficult is it to onboard a new customer domain?

The process is designed to take about two minutes and often requires no support intervention. Ark detects the customer's DNS provider and gives them precise, plain-language instructions. For supported providers like Cloudflare, it can configure the necessary DNS records automatically, making the process self-service.

What is included in the $29/month starter plan?

The starter plan begins with the capacity to manage 10 customer domains and send up to 50,000 emails per month. It includes all core features: white-label email, automated DNS setup, per-tenant isolation, comprehensive logs and analytics, and unlimited team member seats. Pricing scales transparently as your domain and email volume grows.

How do participants access their onboarding page?

Participants access their onboarding entirely without passwords. You simply send them a unique, secure link. When they click the link, they are taken directly to their personalized, branded task page where they can view and complete their assigned actions. This eliminates login friction and simplifies the user experience.

Does Onthen integrate with my existing CRM?

Yes, Onthen is built to sync seamlessly with your CRM. It connects data from onboarding tasks—such as form submissions, file uploads, and completion statuses—directly to the relevant contact or company record in your CRM. This includes updating custom fields and adding a timeline of activities, ensuring all information is centralized.

Can I customize the tasks and their order?

Absolutely. You have full control over designing your onboarding flows. You can create tasks in a specific sequence that must be completed in order, or set up a flexible list where tasks can be done in any order. You can also set dynamic due dates and build reusable templates for different onboarding scenarios.

How does Onthen handle reminders and follow-ups?

Onthen automates follow-ups to save you time. The system automatically sends gentle reminder emails to participants when tasks become overdue. Additionally, it can send weekly summary digests to both participants and your team, keeping everyone informed of progress and pending items without any manual effort from your side.

Ark is an AI-first email API designed for modern developers who build with coding assistants. It belongs to the category of transactional email services, providing the infrastructure for sending automated emails like user verification and notifications directly from an application's code. Users may look for alternatives for various reasons. Common factors include specific pricing needs, such as requiring a free tier or a different volume-based structure. Others might prioritize certain technical features, platform-specific integrations, or a more traditional developer experience that doesn't center on AI tooling. When evaluating alternatives, key considerations are delivery speed and reliability, the clarity of documentation and SDKs, security features like automatic authentication, and overall cost structure. The best choice depends on your project's specific technical requirements and workflow preferences.

Onthen is a customer onboarding platform that automates and centralizes the process using branded, collaborative checklists. It eliminates manual email chains by providing a single page for all participants to track and complete tasks, syncing data directly with your CRM. Users often explore alternatives to find a solution that better fits their budget, specific feature requirements, or existing software ecosystem. Some may need deeper integrations, different pricing models, or a platform that scales with very specific operational workflows. When evaluating alternatives, prioritize tools that offer clear automation, reduce administrative friction, and provide reliable CRM synchronization. The goal is to find a system that creates a seamless, professional experience for both your team and your new clients.