Sleek Design Mobile Apps

Designing with Sleek


Overview

sleek.design is an AI-powered mobile app design tool. You interact with it via a REST API at /api/v1/* to create projects, describe what you want built in plain language, and get back rendered screens. All communication is standard HTTP with bearer token auth.

Base URL: https://sleek.design Auth: Authorization: Bearer $SLEEK_API_KEY on every /api/v1/* request Content-Type: application/json (requests and responses) CORS: Enabled on all /api/v1/* endpoints Parsing responses: write the body to a file (curl -o run.json) and parse the file. Don't pipe JSON through echo: in zsh it expands the escaped \n inside string values into real newlines, which makes the body invalid JSON. API docs: OpenAPI spec at https://sleek.design/api/v1/spec.json; browsable docs at https://sleek.design/api/v1/docs. Fetch the spec for any contract detail not covered here.

Prerequisites: API Key

If SLEEK_API_KEY is not set, use the device flow so the user never handles the raw key:

1. POST https://sleek.design/api/v1/device/start (no auth) with body {"source": "your-tool-slug"}. The response contains a verificationUrl, a human-checkable userCode, a secret deviceCode, and a poll interval in seconds.
2. Show the user the verificationUrl and the userCode, and tell them to confirm the code matches before approving.
3. Poll POST https://sleek.design/api/v1/device/poll with {"deviceCode": "..."} every interval seconds. When the user approves, the poll returns {"status": "approved", "key": "sk_..."} exactly once: store it as SLEEK_API_KEY. Codes expire after 15 minutes; on expired, start over.

Fallback: send the user to https://sleek.design/agents/setup, which handles sign-in, plan upgrade, and key creation in one place, and ask them to paste the key back to you. Keys can also be managed at https://sleek.design/dashboard/api-keys. The full key value is shown only once at creation.

Plans: free accounts can try the API with their one-time trial credits (about one design run), so a new user can see their first design before any payment decision. Sustained use requires the Pro plan or higher ($49.99/month, or $30/month billed yearly at $360/year; includes 20,000 monthly AI credits, roughly 650 screens). When cost becomes relevant (the user asks, an upgrade is needed to continue, or you're about to send them to a payment page), state this pricing plainly, including the yearly option. Never let a payment step come as a surprise.

Key scopes

Create a key with only the scopes needed for the task.

Security & Privacy

• Single host: All requests go exclusively to https://sleek.design. No data is sent to third parties.
• HTTPS only: All communication uses HTTPS. The API key is transmitted only in the Authorization header to Sleek endpoints.
• Minimal scopes: Create API keys with only the scopes required for the task. Prefer short-lived or revocable keys.
• Image URLs: When using imageUrls in chat messages, those URLs are fetched by Sleek's servers. Avoid passing URLs that contain sensitive content.

Designing

The full request/response shapes for every endpoint used below are in the API reference.

1. Create a project

Create a project with POST /api/v1/projects if one doesn't exist yet. Derive a name from the request.

Each project has its own theme, style, and design system. If the user wants multiple design variations, create a separate project for each variation.

2. Send a chat message

Send the request with POST /api/v1/projects/:id/chat/messages. Sleek plans screen content and layout from your message, and will invent a visual style if you don't give it one. Don't decompose the request into screens and don't add product details the user didn't ask for; send the full intent as a single message. If the user described specific screens, include those. Sleek produces richer designs when given room to plan.

Author a style direction: write one whenever the user has given you anything to ground it in — reference images, apps they like, vibe adjectives, things to avoid — or whenever you're producing variations, one direction per variation. Pass the request through unchanged only when it's bare. A style direction is a single comprehensive paragraph, included in the message, covering mood (2–3 adjectives), color strategy (the logic, not hex codes), typography feel, layout philosophy, component style (radii, borders vs shadows, nav treatment), imagery and illustration style, and one or two distinctive details. Commit to a palette, a type direction, and an overall feel — anything that only sets a mood reads as a hint, not a direction. Be opinionated; don't hedge. Put the personality in color, type, and imagery rather than in unusual layout or navigation.

Extend what the user gave you and never contradict it. When they point at reference images or apps they like, study each one and carry what you take into the direction — Sleek only sees images passed as imageUrls, so for anything local the direction is how those references reach it. Borrow patterns, never the source's branding, content, or name.

Use a style direction or a referenceId, not both — a reference already carries a full style guide of its own.

Seed a style with a reference: Sleek curates a catalog of design references. When the user wants a specific look or asks for style options, list them with GET /api/v1/references (each has a name and previewImageUrls you can show) and pass the chosen id as referenceId on the first message to a project, so its style guide seeds the whole design.

Identify your tool: always send source, the slug of the tool making the request. The Sleek editor uses it to show the user who is designing while the run streams. Recognized values: claude-code, claude, codex, chatgpt, cursor, openclaw, grok. If your tool isn't listed, send a short kebab-case slug for it anyway (max 64 chars). Unrecognized values are fine and get a generic label.

Watch it live: runs render in the Sleek editor in real time. After sending the first message to a project, tell the user they can watch their screens being designed live in Sleek, and share the editor link: https://sleek.design/project/:projectId. Don't open a browser yourself unless the user asks.

Polling: chat messages are async by default: you get a runId and poll GET /api/v1/projects/:id/chat/runs/:runId. Start at 2s interval, back off to 5s after 10s, give up after 5 minutes. Exit on completed or failed; if you can't read the status, stop and report it rather than counting it as "not done yet". You can also use ?wait=true for a blocking call (up to 300s; falls back to polling if it times out with 202).

Editing a specific screen: use target.screenId to direct changes to the right screen. The screenId comes from the run's result.operations or from the screenId field on each component returned by GET /api/v1/projects/:id/components; it is not the component ID.