What Is an API-First CMS?
An API-first CMS treats the API as the primary delivery interface for every channel. It is designed that way from the start rather than bolted onto a traditional web editor. Content is created and managed in a dashboard, then delivered exclusively over HTTP endpoints that any application can consume.
A monolithic CMS ships the database, the templating layer, and the frontend as one application, so the presentation layer and the content layer are coupled. In an API-first architecture:
- Content lives in a managed cloud platform
- Your application, whatever it is, fetches content over HTTPS
- There is no shared server, no templating language, no frontend dependency
The same content reaches a Next.js site, a React Native app, an email template, a digital display, or a voice interface from one source of truth.
API-first vs headless
Every API-first CMS is headless. The reverse is not always true. Some headless products expose an API as a secondary path while the editing model still assumes one website: page trees, template fields, preview tied to a single frontend. API-first means the API contract is the product surface, and every capability in the dashboard is reachable programmatically.
What You Get With Cosmic
- REST API with sub-100ms cached responses, globally cached at the edge
- Typed TypeScript SDK (
@cosmicjs/sdk) with a chainable query interface - Content modeling in the dashboard, no schema files and no migration scripts
- First-class relationships between Object Types, expanded inline on request
- AI agents and an MCP server that operate on the same API your frontend uses
- Free plan with full REST API access and no credit card
Cosmic processes over 50 million API requests per month for customers in 150+ countries. Uptime is guaranteed at 99.95% on Enterprise plans, and historical uptime is public at cosmicstatus.com.
Query Your Content in Four Lines
Install the official SDK:
npm install @cosmicjs/sdk
Create a client and query:
import { createBucketClient } from '@cosmicjs/sdk' const cosmic = createBucketClient({ bucketSlug: process.env.COSMIC_BUCKET_SLUG as string, readKey: process.env.COSMIC_READ_KEY as string, }) // Fetch published articles, typed end to end const { objects: articles } = await cosmic.objects .find({ type: 'articles', 'metadata.status': 'published', }) .props('id,title,slug,metadata') .sort('-created_at') .limit(20)
The SDK wraps a plain REST endpoint, so any HTTP client in any language works too:
curl "https://api.cosmicjs.com/v3/buckets/{bucket-slug}/objects?type=articles&status=published&read_key={read_key}"
One query pattern, any framework. There is no proprietary query language to learn.
Built for API-First Teams
Content modeling without schema files
Object Types and their fields are managed in the dashboard. Add a field and it is available in the API immediately, with no repository change and no deploy. Supported field types include text, textarea, markdown, rich text, number, date, switch, select, multi-select, radio, checkboxes, file and files (with imgix transformations), single and multi object relationships, repeaters, JSON, color, and emoji.
Relationships are first-class. A post links to an author, a product links to a category, and the API returns related objects expanded inline or as references depending on how you query. Full walkthrough in the content modeling guide.
Field selection that keeps payloads small
.props() limits the response to the fields you actually render, which keeps mobile payloads small and cache hit rates high. Media served through the image CDN is transformed on the fly with query parameters, so one upload serves every breakpoint.
Webhooks for event-driven builds
Webhooks fire on content lifecycle events: object created, updated, published, unpublished, deleted. Payloads include the full object, so downstream services do not need a follow-up call. Use them to invalidate a CDN cache, trigger a build, or notify Slack. Webhooks are a feature add-on at $99/month, and are also included in the $199/month add-on bundle with Localization, Revision History, and Automatic Backups.
Multi-bucket environments
A project can hold several Buckets: staging and production, separate brands, separate regions. The API shape is identical across buckets, so pointing an app at a different bucket is one environment variable.
AI agents on the same API
Cosmic ships autonomous agents that read and write content through the same endpoints your frontend uses. Content agents research, write, generate images, and create objects on a schedule. Code agents connect to GitHub, open pull requests, and deploy. Team agents live in Slack, WhatsApp, and Telegram. The MCP server exposes your bucket to MCP-compatible tools such as Cursor and Claude Code as native tool calls inside the editor.
API-First Architecture: How It Fits Together
┌─────────────────────────────────────────┐ │ Content Team │ │ Creates content in Cosmic Dashboard │ └─────────────────┬───────────────────────┘ │ ▼ ┌─────────────────────────────────────────┐ │ Cosmic REST API │ │ api.cosmicjs.com/v3/buckets/{slug}/... │ │ Sub-100ms cached · Global · HTTPS │ └────────┬──────────────┬─────────────────┘ │ │ ▼ ▼ ┌─────────────┐ ┌─────────────────────────┐ │ Next.js App │ │ React Native App │ │ (Web) │ │ (iOS / Android) │ └─────────────┘ └─────────────────────────┘ │ │ ▼ ▼ ┌─────────────┐ ┌─────────────────────────┐ │ Email │ │ Digital Displays / IoT │ │ Templates │ │ Custom Integrations │ └─────────────┘ └─────────────────────────┘
One API. One source of truth. Delivered to any channel.
What an API-First CMS Costs
Last verified: September 1, 2026. Source: cosmicjs.com/pricing, fetched September 1, 2026.
| Plan | Price | Buckets | Team members | Objects | Non-cached API calls/mo |
|---|---|---|---|---|---|
| Free | $0/month | 1 | 2 | 1,000 | 10,000 |
| Builder | $99/month | 2 | 3 | 5,000 | 15,000 |
| Team | $299/month | 3 | 5 | 20,000 | 25,000 |
| Business | $499/month | 5 | 10 | 50,000 | 150,000 |
| Enterprise | Custom | Custom | Custom | Custom | Custom |
Every plan includes the REST API, the TypeScript SDK, the CLI, the MCP server, AI agents and workflows, and Cosmic Insights analytics. Additional team members are $29/user/month and additional buckets are $29/bucket/month. Cached API requests are metered separately and start at 100,000/month on Free, rising to 1M/month on Business.
Teams Running on the API
"Cosmic is: us never having to ask a developer to change anything on the backend of our website."
Maximilian Wuhr, Co-Founder at FINN
FINN is a car subscription platform that powers its marketing site on Cosmic's REST API with full editorial autonomy. Editors publish, the API delivers, developers stay on product work.
Other companies building on Cosmic: Parque Explora, Plato, Vuetify, Tripwire Interactive, Cipher Sports, Eastman Music, Prairie Robotics, and Integral Privacy Technologies. Cosmic is a Y Combinator company (W19).
Start Building Free
The free plan includes full REST API access, 1 Bucket, 2 team members, 1,000 Objects, and AI tokens. No credit card required.
Evaluating for a larger team or an enterprise architecture review? Book a call with Tony, Cosmic's CEO.
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