Why we chose the open-source + cloud model for a developer tool in 2026

When we started building Colign, we had a fundamental choice: closed-source SaaS or open-source core with a commercial cloud. We chose open source — and it's been the best decision we've made.

The model

Open-source core (AGPL-3.0):

• Change engine and API server (Go)
• Web app (Next.js — editor, collaboration UI, dashboard)
• MCP Server (Streamable HTTP + stdio)
• Docker Compose for self-hosting
• Helm charts for Kubernetes deployment

Commercial cloud (Colign Cloud):

• Managed hosting with zero ops
• Real-time collaboration at scale
• Team management, roles, and permissions
• SSO, audit logs, and compliance features
• OAuth 2.1 with PKCE for MCP authentication
• SLA guarantees and priority support

The core is free and self-hostable. The cloud is paid and provides value beyond what self-hosting offers.

Why open source matters for spec platforms

Spec platforms occupy a unique position in the development stack: they sit between human decisions and AI execution. This position demands trust that closed-source SaaS can't fully provide.

Trust through transparency

Your specs contain your product strategy, technical decisions, and business logic. When a spec platform is closed-source, you're trusting a black box with your most sensitive engineering artifacts.

Open source means:

• You can audit exactly what Colign does with your data
• You can verify that specs are stored and transmitted securely
• You can inspect how MCP tools expose your data to AI agents
• No vendor lock-in — your data and workflow are portable

Self-hosting for compliance

Some organizations can't use cloud services for their specs:

• Defense contractors with air-gapped networks
• Financial institutions with data residency requirements
• Healthcare companies under HIPAA
• Government agencies with FedRAMP requirements

Open source with Docker Compose and Helm charts means these organizations can run Colign on their own infrastructure, behind their own firewalls, under their own security policies.

Community-driven ecosystem

The spec-driven development ecosystem is still emerging. MCP integrations, AI agent workflows, and spec templates are being invented in real-time. Open source enables:

• Community-built MCP tool extensions
• Custom workflow gates for specific team processes
• Integration adapters for existing tools (Linear, Jira, GitHub)
• Spec templates for different domains (mobile, infrastructure, ML)

A closed-source platform would bottleneck all of this behind our roadmap. Open source lets the community build what they need.

Why AGPL-3.0?

We chose AGPL-3.0 specifically because it protects the open-source ecosystem while allowing legitimate self-hosting:

• Self-hosting for internal use: Fully permitted. Run Colign on your servers for your team.
• Modifications for internal use: Fully permitted. Customize Colign for your workflow.
• Offering Colign as a service: Requires sharing your modifications. This prevents cloud providers from taking the code and competing without contributing back.

AGPL-3.0 is the license that says: "Use it freely, but if you build a service on it, share your improvements."

The business model

Colign Cloud is how we sustain development:

• Free tier: Small teams can use Colign Cloud at no cost — we want adoption
• Team tier: Real-time collaboration, workflow gates, MCP server, team roles
• Enterprise tier: SSO (SAML/OIDC), audit logs, dedicated infrastructure, SLA, OAuth 2.1 PKCE for MCP

The economics work because the cloud provides genuine operational value: zero-downtime upgrades, managed PostgreSQL and Redis, global CDN, real-time WebSocket infrastructure (Hocuspocus/Y.js), and 24/7 monitoring.

Self-hosting is free but not free of cost — you manage the infrastructure, upgrades, backups, and scaling. The cloud abstracts all of that.

The developer tool landscape

This model is proven. Supabase, GitLab, Sentry, PostHog — the most trusted developer tools are open-source core with commercial cloud. Developers adopt tools they can inspect, and they pay for tools that save them operational overhead.

We believe specs are too important to be locked in a proprietary platform. Your specs should be yours — to read, export, self-host, and extend. That's the promise of open source, and it's the promise we're making.

FAQ

Q: Can I use Colign for free? A: Yes. Self-host the open-source core for free, or use Colign Cloud's free tier for small teams.

Q: What's the difference between self-hosted and cloud? A: Same core features. Cloud adds managed infrastructure, OAuth 2.1 PKCE for MCP, SSO, audit logs, and SLA. Self-hosted means you manage the infrastructure.

Q: Will the open-source core ever be limited to push people to the cloud? A: No. The core includes all spec lifecycle features: structured proposals, acceptance criteria, tasks, workflow states, MCP server, real-time co-editing. Enterprise features (SSO, audit logs) are cloud-only because they require centralized infrastructure.