First-party app
HTML/CSS to Image

HTML/CSS to Image

Render HTML/CSS, web pages and saved templates to images and PDFs with HTML/CSS to Image (hcti.io).

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About

HTML/CSS to Image ships in the w6w first-party pack. It declares 12 actions, 2 health checks, and the host runs its code in a sandbox that never sees the credential.

App id
io.w6w.htmlcsstoimage
Version
0.1.0
Author
w6w
Licence
MIT
Categories
Developer Tools · Marketing

Overview

HTML/CSS to Image turns markup into pictures: send HTML and CSS, a public URL, or the values for a saved template, and get back a permanent image URL (PNG, JPG, WebP or PDF) served from a CDN. It is the usual way to generate social cards, receipts, certificates, product graphics and page screenshots from a workflow without running a browser.

This app covers the three ways to create an image (HTML/CSS, URL screenshot, and a saved template, optionally pinned to a version), reading and listing the images an account has made, deleting them, and the template lifecycle: create a template, save a new version of it, list templates and their versions, and remove one. It also reads the account’s image usage by hour, day, month and billing period.

Image creation spends image credits on the vendor’s side, so none of the creation actions is marked retry-safe; use the vendor’s duplicate-detection window (dedupe_duration_s) when a retry could otherwise bill twice.

Build with HTML/CSS to Image

Three routes to the same 12 actions. The Workflow tab is generated from HTML/CSS to Image's own manifest and carries its real ids, so it is copy-pasteable; the Code and CLI examples are the same call for any action on any app, so every app-specific value in them is a blank you fill in.

Create Image from HTML/CSS

image-create-html

Render HTML and CSS to an image (PNG, JPG, WebP) or PDF and get its URL.

Create Image from Template

image-create-template

Render a saved template with your values to an image or PDF.

Create Image from URL

image-create-url

Screenshot a public web page to an image (PNG, JPG, WebP) or PDF.

Delete Image

image-delete

Permanently delete an image and its cached copies.

Get Image

image-get

Read the metadata of an image: how it was created, its options and timestamps.

List Images

image-list

List created images, 50 per page, with a continuation token.

Create Template

template-create

Save an HTML/CSS template with Handlebars variables for later rendering.

Delete Template

template-delete

Remove a template and all its versions.

List Templates

template-list

List saved templates with their latest version.

Create Template Version

template-version-create

Save a new version of an existing template; renders without a pinned version use it.

List Template Versions

template-versions-list

List the saved versions of a template (the way to read one template's HTML/CSS).

Get Usage

usage-get

Read images created per hour, day, month and billing period.

A workflow step names the app and the action, and the editor fills in the connection when you pick one. This is the Step shape from the workflow spec, carrying HTML/CSS to Image's real ids.

{
  "manifestVersion": "2",
  "name": "htmlcsstoimage-example",
  "steps": [
    {
      "id": "image-create-html",
      "uses": {
        "app": "io.w6w.htmlcsstoimage",
        "action": "image-create-html",
        "connection": "conn_YOUR_CONNECTION_ID"
      },
      "with": {
        "html": "<html>"
      }
    }
  ]
}

Here are some of the things you can do

  • Create Image from HTML/CSS

    perform
    image-create-html
  • Create Image from Template

    perform
    image-create-template
  • Create Image from URL

    perform
    image-create-url
  • Get Image

    read
    image-get
  • List Images

    read
    image-list

+7 more actions available

Every app-specific value here is a blank you have to fill in. An app action is reached through the connection that authenticates it, so the address is a connection id, not the app id — and connections belong to your account, so a public page cannot know yours. Create one for HTML/CSS to Image, then fill in the three blanks: conn_YOUR_CONNECTION_ID, the action key, and the parameters that action declares. The call itself is real — the shape is transcribed from the studio's own snippet builder, which prints the same kind of blanks — but nothing in it is specific to HTML/CSS to Image. The Workflow tab is where this app's real ids are.

Install
npm install @w6w/sdk
yarn add @w6w/sdk
pnpm add @w6w/sdk
deno add npm:@w6w/sdk
Code
import { W6wClient, isActionRun } from "@w6w/sdk";

// Reads W6W_BASE_URL and W6W_TOKEN from the environment when omitted.
const client = new W6wClient();

const envelope = await client.run({
  urn: "conn_YOUR_CONNECTION_ID",
  action: "image-create-html",
  payload: {
    html: "<value>",
    // css: "<value>",
    // google_fonts: "<value>",
    // format: "<value>",
    // device_scale: "<value>",
    // viewport_width: "<value>",
    // viewport_height: "<value>",
    // selector: "<value>",
    // ms_delay: "<value>",
    // max_wait_ms: "<value>",
    // color_scheme: "<value>",
    // media_type: "<value>",
    // timezone: "<value>",
    // transparent_background: "<value>",
    // render_when_ready: "<value>",
    // dedupe_duration_s: "<value>",
    // metadata: "<value>",
    // pdf_options: "<value>",
  },
});

if (isActionRun(envelope)) console.log(envelope.value);
Install the CLI
npm install -g @w6w/cli
CLI
w6w run conn_YOUR_CONNECTION_ID --action image-create-html --payload '{"html":"<value>"}'

Give an AI agent HTML/CSS to Image — without giving it HTML/CSS to Image's credentials. One MCP endpoint exposes every app, function and workflow the caller is entitled to, as tools it can discover and run. Access is granted per team while we onboard.

One tool call
{
  "name": "w6w_invoke",
  "arguments": {
    "ref": "app:io.w6w.htmlcsstoimage#image-create-html",
    "input": {
      "html": "<html>"
    }
  }
}

Every tool names its target with a single ref. The app: form above doesn't name a connection at all — the host resolves which of the caller's HTML/CSS to Image connections to sign with, and refuses rather than guesses when the answer is ambiguous.

What the agent gets

Credentials it can't read

The token is attached host-side, at the moment of the call. It is never a tool argument, never in the model's context, and never in a transcript — so a prompt injection has nothing to exfiltrate.

A tool surface scoped to the caller

Tools are derived per end user from what that person has actually connected and is entitled to — not one shared bot identity carrying the union of everyone's access.

A durable workflow in one call

Multi-step work runs on the workflow engine and returns a run handle the agent can poll — retries, branching and state survive the conversation that started them.

Health-aware discovery

HTML/CSS to Image's declared health checks are on the surface too, so an agent can tell "the vendor is down" from "your credential expired" before it burns a retry on either.

The MCP surface is part of the hosted platform. HTML/CSS to Image itself is MIT, and the runtime that executes it is source-available (FSL).

Request MCP access

Health checks

HTML/CSS to Image declares its own checks, so its health is a property of the app rather than something the host guesses at.

service

HTML/CSS to Image API status

Status of the `API` component (hcti.io) on status.htmlcsstoimage.com; the website and dashboard component is reported as detail and never decides the verdict.

quota

Image credit headroom