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

Prerequisites: API Key

Create API keys at https://sleek.design/dashboard/api-keys. The full key value is shown only once at creation — store it in the SLEEK_API_KEY environment variable.

Required plan: Pro or higher (API access is gated)

Key scopes

Scope	What it unlocks
`projects:read`	List / get projects
`projects:write`	Create / delete projects
`components:read`	List components in a project
`chats:read`	Get chat run status
`chats:write`	Send chat messages
`screenshots`	Render component screenshots

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.

Quick Reference — All Endpoints

Method	Path	Scope	Description
`GET`	`/api/v1/projects`	`projects:read`	List projects
`POST`	`/api/v1/projects`	`projects:write`	Create project
`GET`	`/api/v1/projects/:id`	`projects:read`	Get project
`DELETE`	`/api/v1/projects/:id`	`projects:write`	Delete project
`GET`	`/api/v1/projects/:id/components`	`components:read`	List components
`GET`	`/api/v1/projects/:id/components/:componentId`	`components:read`	Get component
`POST`	`/api/v1/projects/:id/chat/messages`	`chats:write`	Send chat message
`GET`	`/api/v1/projects/:id/chat/runs/:runId`	`chats:read`	Poll run status
`POST`	`/api/v1/screenshots`	`screenshots`	Render screenshot

All IDs are stable string identifiers.

Endpoints

Projects

List projects

GET /api/v1/projects?limit=50&offset=0
Authorization: Bearer $SLEEK_API_KEY

Response 200:

{
  "data": [
    {
      "id": "proj_abc",
      "name": "My App",
      "slug": "my-app",
      "createdAt": "2026-01-01T00:00:00Z",
      "updatedAt": "..."
    }
  ],
  "pagination": { "total": 12, "limit": 50, "offset": 0 }
}

Create project

POST /api/v1/projects
Authorization: Bearer $SLEEK_API_KEY
Content-Type: application/json

{ "name": "My New App" }

Response 201 — same shape as a single project.

Get / Delete project

GET    /api/v1/projects/:projectId
DELETE /api/v1/projects/:projectId   → 204 No Content

Components

List components

GET /api/v1/projects/:projectId/components?limit=50&offset=0
Authorization: Bearer $SLEEK_API_KEY

Response 200:

{
  "data": [
    {
      "id": "cmp_xyz",
      "name": "Hero Section",
      "activeVersion": 3,
      "versions": [{ "id": "ver_001", "version": 1, "code": "<!DOCTYPE html>...</html>", "createdAt": "..." }],
      "createdAt": "...",
      "updatedAt": "..."
    }
  ],
  "pagination": { "total": 5, "limit": 50, "offset": 0 }
}

Get component

Fetches a single component by ID. Use this when you need the code for a specific screen (e.g., after a chat run returns a componentId in its operations).

GET /api/v1/projects/:projectId/components/:componentId
Authorization: Bearer $SLEEK_API_KEY

Response 200 — same shape as a single item from the list endpoint:

{
  "data": {
    "id": "cmp_xyz",
    "name": "Hero Section",
    "activeVersion": 3,
    "versions": [{ "id": "ver_001", "version": 1, "code": "<!DOCTYPE html>...</html>", "createdAt": "..." }],
    "createdAt": "...",
    "updatedAt": "..."
  }
}

Chat — Send Message

This is the core action: describe what you want in message.text and the AI creates or modifies screens.

POST /api/v1/projects/:projectId/chat/messages?wait=false
Authorization: Bearer $SLEEK_API_KEY
Content-Type: application/json
idempotency-key: <optional, max 255 chars>

{
  "message": { "text": "Add a pricing section with three tiers" },
  "imageUrls": ["https://example.com/ref.png"],
  "target": { "screenId": "scr_abc" }
}

Field	Required	Notes
`message.text`	Yes	1+ chars, trimmed
`imageUrls`	No	HTTPS URLs only; included as visual context
`target.screenId`	No	Edit a specific screen using its `screenId` (not `componentId`); omit to let AI decide
`?wait=true/false`	No	Sync wait mode (default: false)
`idempotency-key` header	No	Replay-safe re-sends

Response — async (default, `wait=false`)

Status 202 Accepted. result and error are absent until the run reaches a terminal state.

{
  "data": {
    "runId": "run_111",
    "status": "queued",
    "statusUrl": "/api/v1/projects/proj_abc/chat/runs/run_111"
  }
}

Response — sync (`wait=true`)

Blocks up to 300 seconds. Returns 200 when completed, 202 if timed out.

{
  "data": {
    "runId": "run_111",
    "status": "completed",
    "statusUrl": "...",
    "result": {
      "assistantText": "I added a pricing section with...",
      "operations": [
        { "type": "screen_created", "screenId": "scr_xyz", "screenName": "Pricing", "componentId": "cmp_xyz" },
        { "type": "screen_updated", "screenId": "scr_abc", "componentId": "cmp_abc" },
        { "type": "theme_updated" }
      ]
    }
  }
}

Chat — Poll Run Status

Use this after async send to check progress.

GET /api/v1/projects/:projectId/chat/runs/:runId
Authorization: Bearer $SLEEK_API_KEY

Response — same shape as send message data object:

{
  "data": {
    "runId": "run_111",
    "status": "queued",
    "statusUrl": "..."
  }
}

When completed successfully, result is present:

{
  "data": {
    "runId": "run_111",
    "status": "completed",
    "statusUrl": "...",
    "result": {
      "assistantText": "...",
      "operations": [...]
    }
  }
}

When failed, error is present:

{
  "data": {
    "runId": "run_111",
    "status": "failed",
    "statusUrl": "...",
    "error": { "code": "execution_failed", "message": "..." }
  }
}

Run status lifecycle: queued → running → completed | failed

Screenshots

Takes a snapshot of one or more rendered components.

POST /api/v1/screenshots
Authorization: Bearer $SLEEK_API_KEY
Content-Type: application/json

{
  "componentIds": ["cmp_xyz", "cmp_abc"],
  "projectId": "proj_abc",
  "format": "png",
  "scale": 2,
  "gap": 40,
  "padding": 40,
  "background": "transparent"
}

Field	Default	Notes
`format`	`png`	`png` or `webp`
`scale`	`2`	1–3 (device pixel ratio)
`gap`	`40`	Pixels between components
`padding`	`40`	Uniform padding on all sides
`paddingX`	(optional)	Horizontal padding; overrides `padding` for left/right when provided
`paddingY`	(optional)	Vertical padding; overrides `padding` for top/bottom when provided
`paddingTop`	(optional)	Top padding; overrides `paddingY` when provided
`paddingRight`	(optional)	Right padding; overrides `paddingX` when provided
`paddingBottom`	(optional)	Bottom padding; overrides `paddingY` when provided
`paddingLeft`	(optional)	Left padding; overrides `paddingX` when provided
`background`	`transparent`	Any CSS color (hex, named, `transparent`)
`showDots`	`false`	Overlay a subtle dot grid on the background

Padding resolves with a cascade: per-side → axis → uniform. For example, paddingTop falls back to paddingY, which falls back to padding. So { "padding": 20, "paddingX": 10, "paddingLeft": 5 } gives top/bottom 20px, right 10px, left 5px.

When showDots is true, a dot pattern is drawn over the background color. The dots automatically adapt to the background: dark backgrounds get light dots, light backgrounds get dark dots. This has no effect when background is "transparent".

Always use "background": "transparent" unless the user explicitly requests a specific background color.

Response: raw binary image/png or image/webp with Content-Disposition: attachment.

Error Shapes

{ "code": "UNAUTHORIZED", "message": "..." }

HTTP	Code	When
401	`UNAUTHORIZED`	Missing/invalid/expired API key
403	`FORBIDDEN`	Valid key, wrong scope or plan
404	`NOT_FOUND`	Resource doesn't exist
400	`BAD_REQUEST`	Validation failure
409	`CONFLICT`	Another run is active for this project
500	`INTERNAL_SERVER_ERROR`	Server error

Chat run-level errors (inside data.error):

Code	Meaning
`out_of_credits`	Organization has no credits left
`execution_failed`	AI execution error

Prompting Sleek

Sleek has its own AI that plans screen content, visual style, and layout. Pass the user's request to Sleek as-is — don't add details the user didn't ask for. If the user described specific screens and styling, include those. If they just said "build me a running app," send that and let Sleek decide the rest. Sleek produces richer designs when given room to plan, so avoid inventing screen content or layout details that the user didn't specify.

Designing

1. Create a project

Create a project with POST /api/v1/projects if one doesn't exist yet. Ask the user for a name, or derive one 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

Describe what to build using POST /api/v1/projects/:id/chat/messages. You can use the user's words directly — Sleek's AI interprets natural language. You do not need to decompose the request into screens; send the full intent as a single message and let Sleek decide what screens to create.

Chat messages are async by default — you get a runId and poll for completion with GET /api/v1/projects/:id/chat/runs/:runId. You can also use ?wait=true for a blocking call (up to 300s; falls back to polling if it times out with 202).

Polling: start at 2s interval, back off to 5s after 10s, give up after 5 minutes.

Editing a specific screen: use target.screenId to direct changes to the right screen (uses the screen ID from operations, not the component ID).

One run at a time: only one active run is allowed per project. If you get 409 CONFLICT, wait for the current run to complete before sending the next message. Messages to different projects can run in parallel — use async polling (not ?wait=true) when running multiple projects concurrently.

Safe retries: add an idempotency-key header (≤255 chars) to replay-safe re-sends. The server returns the existing run rather than creating a duplicate.

3. Show the results

After every chat run that produces screen_created or screen_updated operations, always take screenshots and show them to the user using POST /api/v1/screenshots. Never silently complete a chat run without delivering the visuals.

New screens: one screenshot per screen + one combined screenshot of all screens in the project.
Updated screens: one screenshot per affected screen.

Use background: "transparent" for all screenshots unless the user explicitly requests otherwise.

Save screenshots in the project directory (not a temporary folder) so the user can easily view them.

Implementing Designs

When the user wants to implement the designs in code (not just preview them), always fetch the component HTML code — do not rely on screenshots alone.

Use GET /api/v1/projects/:id/components/:componentId to fetch each screen's code. The componentId comes from the chat run's result.operations.

HTML prototypes

The component code is a complete HTML document — save it directly to a .html file. No build step needed.

Native frameworks (React Native, SwiftUI, etc.)

Use both the HTML code and the screenshots together:

HTML code is the implementation reference — it contains the exact structure, layout, styling, colors, spacing, content, image URLs, and icon names.
Screenshots are the visual target — use them to verify your implementation matches the intended look.

The HTML tells you how to build it; the screenshot tells you what it should look like.

Icons

Sleek uses Iconify icons in the format prefix:name (e.g., solar:heart-bold, material-symbols:search-rounded, lucide:settings). The most common sets are Solar, Hugeicons, Material Symbols and MDI.

Use the exact icons from the HTML code — do not substitute with a different icon set. Matching icons is important for design fidelity.

When implementing icons:

Check if the project already has an icon system that supports the same sets Sleek uses (Solar, Hugeicons, Material Symbols, MDI). If so, use it. Note: @expo/vector-icons does not support these sets — do not use it as a substitute.
Otherwise, fetch the SVGs from the Iconify API and embed them in the code:
```
GET https://api.iconify.design/{prefix}/{name}.svg
```
Example: https://api.iconify.design/solar/heart-bold.svg

Collect all icon names from the HTML, fetch their SVGs, and save them as static assets or string constants in the codebase. For React Native / Expo, render them with react-native-svg's SvgXml component — this works in Expo Go with no additional native dependencies.

Fonts

The HTML includes Google Fonts via <link> tags in the <head>. Use the same fonts and weights when implementing in a native framework — extract the font family names and weights from the <link> tags.

Navigation

The designs may include navigation elements like tab bars and headers. Update the project's navigation styling and structure to match the designs — don't just implement the screen content while leaving the default navigation untouched.

Pagination

All list endpoints accept limit (1–100, default 50) and offset (≥0). The response always includes pagination.total so you can page through all results.

GET /api/v1/projects?limit=10&offset=20

Tips

Saving component HTML to files

Component code can be large. When saving it to .html files, avoid writing the content through your text output — this is slow and wastes tokens. Instead, use shell commands to fetch the API response and write it directly to disk (e.g., pipe the response body into a file). This applies to both single and multiple components.

Common Mistakes

Mistake	Fix
Sending to `/api/v1` without `Authorization` header	Add `Authorization: Bearer $SLEEK_API_KEY` to every request
Using wrong scope	Check key's scopes match the endpoint (e.g. `chats:write` for sending messages)
Sending next message before run completes	Poll until `completed`/`failed` before next send
Using `wait=true` on long generations	It blocks 300s max; have a fallback to polling for `202` response
HTTP URLs in `imageUrls`	Only HTTPS URLs are accepted
Assuming `result` is present on `202`	`result` is absent until status is `completed`
Using `screenId` as `componentIds` in screenshots	`screenId` and `componentId` are different; always use `componentId` from operations for screenshots