# Melius vs Subframe

> Melius scores 54.1 (C) to Subframe's 39.7 (E) for design canvases. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/melius-vs-subframe
- Markdown: https://www.anchorterminal.com/compare/melius-vs-subframe.md (~2,250 tokens)
- Slim: https://www.anchorterminal.com/compare/melius-vs-subframe.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/melius-vs-subframe.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

Melius scores 54.1 (C) on agent readiness against Subframe's 39.7 (E), and leads in 4 of 7 scored categories. Subframe leads on payments & pricing. Both do design canvases.

- Melius: grade C, 54.1/100, rank #695 of 950. Markdown https://www.anchorterminal.com/tools/melius.md · JSON https://www.anchorterminal.com/api/v1/tools/melius.json
- Subframe: grade E, 39.7/100, rank #915 of 950. Markdown https://www.anchorterminal.com/tools/subframe.md · JSON https://www.anchorterminal.com/api/v1/tools/subframe.json
- Best design workspace and canvas APIs for AI agents: https://www.anchorterminal.com/best/design/index.md
- All 49 design comparisons: https://www.anchorterminal.com/compare/design/index.md

## Which one, for what

### Melius (C)

Good for: An agent producing batches of ad creative, product images or short videos on a shared canvas that people then review, with many models behind one key.

Ahead on:
- Reliability, 69 against 19
- Schema & documentation, 70 against 54

Also in its favour:
- No incidents deducted, where Subframe loses 3 points for them

Watch for: API keys have no scopes. A key works with its creator's role in every team the creator belongs to

### Subframe (E)

Good for: A coding agent working beside a team that designs React and Tailwind interfaces in Subframe and wants the design as code, with a read-only route for review.

Ahead on:
- Payments & pricing, 33 against 20

Watch for: 46 tools are documented with no toolsets, and the vendor's `design` skill that explains them is about 55 KB of text


## Score by category

| Category | Weight | Melius | Subframe | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 69 | 19 | Melius +50 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 70 | 54 | Melius +16 |
| Agent ergonomics | 13% (16.2 this run) | 51 | 47 | Melius +4 |
| Security & auth | 14% (17.5 this run) | 43 | 44 | Subframe +1 |
| Payments & pricing | 10% (12.5 this run) | 20 | 33 | Subframe +13 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 66 | 65 | Melius +1 |
| Transparency & trust | 7% (8.8 this run) | 55 | 57 | Subframe +2 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **54.1 · C** | **39.7 · E** | |

## Facts side by side

| Fact | Melius | Subframe |
| --- | --- | --- |
| Kind | HTTP API | MCP server |
| Vendor | Melius AI, Inc. | Atomic Design Inc |
| Hosted endpoint | `https://api.melius.com/api/v1` | `https://mcp.subframe.com/mcp` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Proprietary service under Melius's terms of service. The mel CLI on npm is MIT, with no public source repository found | Proprietary service under Atomic Design's terms of service. `@subframe/cli` and `@subframe/core` are marked ISC in their package files and the Claude Code plugin MIT in its manifest, with no licence file in the repository |
| Tools exposed | 75 | 46 |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-09-10 | 2026-10-08 |
| Terms last updated | no date given | 2026-01-22 |
| Privacy policy last updated | no date given | 2026-01-22 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 9 npm/wk | 435 stars, 1k npm/wk |

## Verdicts

**Melius.** One backend serves a 59-operation REST API with a public OpenAPI spec, a hosted MCP server with OAuth sign-in and a JSON-only CLI, and the status page shows no incidents since July 2026. API keys carry no scopes and work with their creator's role, and no rate-limit numbers, changelog or per-model credit prices are published.

**Subframe.** An agent can read and change pages, components, snippets and themes in a Subframe project through a hosted MCP server with OAuth, and Viewer accounts get a read-only server. The server lists 46 tools, and no status page, rate limits, changelog or security contact were found. Three tools were renamed in September 2026 with no notice found.

## Before you call either

### Melius

1. Generate by creating a node on a canvas, starting a run with POST /nodes/{nodeId}/runs, then polling GET /node-runs/{nodeRunId} until `status` is finished or failed
2. Over MCP, call `get_guide` first, `show_presence` before node changes and `canvas_plan_layout` before `bulk_create_nodes`
3. On 429 wait `Retry-After` seconds. After a timeout or 5xx on a write, read the canvas or run state before resubmitting, because there are no idempotency keys
4. Read credit costs from GET /generation/models?category=image before a bulk run. A 400 can mean the team is out of credits
5. Downloads arrive as a ZIP from a signed URL. Fetch that URL without the `Authorization` header

### Subframe

1. Connect with an MCP client that supports OAuth. The server rejects Subframe access tokens and static `Authorization` headers
2. Pass `projectId` on every call. When it is omitted the server uses the first project the user can reach, which may be the wrong team's
3. After `design_page`, `design_component` or `edit_component`, call `wait_for_jobs` with the `jobId` before reading the result. Earlier reads return stale content
4. Ask the owner before any delete tool or a theme token deletion. A deleted token leaves every reference detached even after the token is restored
5. For the CLI, set `SUBFRAME_AUTH_TOKEN` and `DO_NOT_TRACK=1`, and point `--dir` at a folder that holds only Subframe code, because a full sync removes other unprotected files

## Questions

### Which is better for AI agents, Melius or Subframe?

Melius scores 54.1 (C) on agent readiness against Subframe's 39.7 (E), and leads in 4 of 7 scored categories. Subframe leads on payments & pricing.

### Do Melius and Subframe need an API key?

Both take an API key or an OAuth sign-in.

### Can an agent call Melius and Subframe without installing anything?

Yes. Melius has a hosted endpoint at https://api.melius.com/api/v1 and Subframe at https://mcp.subframe.com/mcp.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/melius-vs-subframe.json, and with the fewest tokens: https://www.anchorterminal.com/compare/melius-vs-subframe.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "melius", "b": "subframe"}`. From a terminal: `anchor compare melius subframe`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/melius.json and https://www.anchorterminal.com/api/v1/tools/subframe.json

## Other comparisons with Melius or Subframe

- [Figma API + MCP vs Melius](https://www.anchorterminal.com/compare/figma-mcp-vs-melius.md)
- [Figma API + MCP vs Subframe](https://www.anchorterminal.com/compare/figma-mcp-vs-subframe.md)
- [Framer Server API vs Melius](https://www.anchorterminal.com/compare/framer-vs-melius.md)
- [Framer Server API vs Subframe](https://www.anchorterminal.com/compare/framer-vs-subframe.md)
- [Melius vs Zeplin](https://www.anchorterminal.com/compare/melius-vs-zeplin.md)
- [Miro API + MCP vs Subframe](https://www.anchorterminal.com/compare/miro-vs-subframe.md)
- [pen.dev vs Subframe](https://www.anchorterminal.com/compare/pen-dev-vs-subframe.md)
- [Penpot API + MCP vs Subframe](https://www.anchorterminal.com/compare/penpot-vs-subframe.md)
- [Sketch vs Subframe](https://www.anchorterminal.com/compare/sketch-vs-subframe.md)
- [Subframe vs Zeplin](https://www.anchorterminal.com/compare/subframe-vs-zeplin.md)
- [Melius vs Miro API + MCP](https://www.anchorterminal.com/compare/melius-vs-miro.md)
- [Melius vs pen.dev](https://www.anchorterminal.com/compare/melius-vs-pen-dev.md)
- [Melius vs Penpot API + MCP](https://www.anchorterminal.com/compare/melius-vs-penpot.md)
- [Melius vs Sketch](https://www.anchorterminal.com/compare/melius-vs-sketch.md)