--- title: Integration options description: Reference for every option of the c15t() Astro integration, the Astro equivalent of a consent provider, from backendURL, mode and routePrefix to ui, theme, i18n, middleware and the client entrypoint. group: frameworks lastModified: "2026-10-10T16:01:45+01:00" --- ## What the integration does Astro islands never share a component tree, so c15t on Astro has no provider component. The `c15t()` integration in `astro.config.mjs` takes its place. It adds four things to your site: * A middleware that resolves consent for each request into `Astro.locals.c15t`, which every component reads. * A page script that starts one consent runtime per page load. Every script and island on the page shares it. * c15t's styles: base and configured IAB banner rules inline in each page, and dialog rules linked before their surface mounts. On a Tailwind CSS 3 site, the full base and configured IAB stylesheets run through your CSS pipeline instead. * In `manifest()` mode, one route at `/api/c15t/[...path]` that answers `/api/c15t/init` and `/api/c15t/manifest`. ```js title="astro.config.mjs" import node from '@astrojs/node'; import svelte from '@astrojs/svelte'; import { defineConfig } from 'astro/config'; import c15t from 'c15t/astro'; export default defineConfig({ adapter: node({ mode: 'standalone' }), integrations: [svelte(), c15t()], output: 'server', }); ``` `c15t()` works with no options: the backend URL comes from `PUBLIC_C15T_BACKEND_URL` and the mode defaults to `manifest()`. List the Astro integration of your `ui` framework before `c15t()`. Import `c15t` and the mode helpers from `c15t/astro`. ## Options must survive JSON The integration serializes its options once at build time and hands the same JSON to the middleware, the components and the browser. Functions, class instances and other live values do not survive that, so `c15t()` throws when an option holds a function, and names where it is. Put callbacks, vendor helpers from `@c15t/integrations` and anything else with a function in `src/c15t.client.ts`, the module [`clientEntrypoint`](#cliententrypoint) names. The options are also written into every page, so keep secrets out of them. The backend URL is public configuration, not a secret. ## `backendURL` Your Inth or self-hosted backend. The browser saves consent there with `POST /subjects`, `hosted()` asks its `/init`, and `manifest()` reads `${backendURL}/manifest`. It defaults to `PUBLIC_C15T_BACKEND_URL`, then `PUBLIC_INTH_PROJECT_URL`, read from the environment or a `.env` file in the project root when `astro.config.mjs` loads. A `hosted({ backendURL })` of its own wins over both. On the server, a relative backend URL or `manifestURL`, such as `/api/self-host`, resolves against the URL Astro gives the request, `Astro.url`. c15t does not read `x-forwarded-host` or other forwarding headers to build it. ## `mode` Where the visitor's policy comes from. Build it with one of the three helpers from `c15t/astro`; they return plain data. Without `mode`, the integration uses `manifest()`. |Helper|Resolves consent|Needs| |--|--|--| |`manifest()`|On your server, from your project's public policy, downloaded during the build|A server adapter and a backend URL| |`manifest({ source: 'runtime' })`|On your server, from the policy fetched and cached at runtime|A server adapter and a backend URL| |`manifest({ resolve: 'browser' })`|In the browser, from the manifest|A backend URL. Works on static output: the integration prerenders `${routePrefix}/manifest`| |`hosted()`|At your backend's `/init`, from the server on request-rendered pages and from the browser otherwise|A backend URL| |`offline()`|In the browser and on your server, with no backend|Nothing. Not recommended for production environments.| `manifest()` accepts: |Field|Type|Effect| |--|--|--| |`source`|`'build' \|'runtime'`|`'build'`, the default, uses the snapshot the build downloaded, or fetches at runtime when the build has none. `'runtime'` always fetches at runtime.| |`snapshot`|`ConsentManifest`|A manifest you supply, used instead of downloading one. Not combined with `source`.| |`resolve`|`'server' \|'browser'`|Where the policy resolves. `'server'` by default.| |`manifestURL`|`string`|Where the manifest is fetched. Defaults to `${backendURL}/manifest`.| |`geoURL`, `inputs`|`string`, `{ country?, region? }`|The visitor's location, for `resolve: 'browser'` only.| `hosted()` accepts: |Field|Type|Effect| |--|--|--| |`backendURL`|`string`|Backend base URL, in place of the top-level `backendURL`. Absolute, or same-origin such as `/api/self-host`| |`headers`|`Record`|Extra headers sent with `/init` from the server and the browser. From the server, only geography, language and privacy-signal headers are sent| `offline()` accepts `policyRules`, the rules to resolve locally. Without them it resolves the recommended rule pack. Choices persist in the visitor's cookie and localStorage only, and there are no consent records. `manifest()` and `hosted()` stop `astro.config` from loading without a backend URL, because the server would have no policy to read and the browser nowhere to save consent. A `manifest({ snapshot })` needs none for the policy. [Rendering and deployment](/docs/frameworks/astro/rendering) explains which mode fits which Astro output. ## `routePrefix` The path of the route the integration injects in `manifest()` mode: `'/api/c15t'` by default. One catch-all, `${routePrefix}/[...path]`, answers `${routePrefix}/init` and `${routePrefix}/manifest`. A page whose consent changes after it loads, such as after a language change, asks it again. The route renders on demand, so `astro build` with `manifest()` needs a server adapter. `manifest({ resolve: 'browser' })` on static output prerenders only `${routePrefix}/manifest`. `hosted()` and `offline()` inject nothing. Set `routePrefix: false` to inject nothing in `manifest()` mode. The browser then asks the backend's `/init`, not a route of your own. See [serve the routes yourself](/docs/frameworks/astro/server#serve-the-routes-yourself). ## Consent and scripts |Option|Type|Default|Effect| |--|--|--|--| |`onBuildError`|`'fail' \|'runtime'`|Unset|What a failed build-time manifest fetch does in `manifest()` mode. Unset, `astro build` stops and `astro dev` logs a warning, and the server fetches the policy at runtime. `'fail'` stops both. `'runtime'` lets both continue. A missing backend URL counts as a failed fetch. The `C15T_ON_BUILD_ERROR` environment variable overrides it. See [build-time manifests](/docs/frameworks/astro/rendering#bundle-the-manifest-during-builds).| |`reportSessions`|`boolean`|`true`|In `manifest()` mode, reports each visitor the server resolves to the backend, so visitor counts stay complete.| |`consentCategories`|`AllConsentNames[]`|Inferred from scripts and the policy|Categories the banner and dialog offer| |`scripts`|`Script[]`|None|Scripts without callbacks, loaded when their category is allowed. See [Scripts](/docs/frameworks/astro/scripts)| |`vendors`|`Vendor[]`|None|Vendors the dialog lists with their own switch inside a category. Merged with vendors from the backend manifest. See [Vendor consent](/docs/frameworks/astro/vendor-consent)| |`networkBlocker`|`{ rules, enabled?, logBlockedRequests? } \|false`|Off|Blocks matching `fetch` and `XMLHttpRequest` calls until consent. See [Network blocker](/docs/frameworks/astro/network-blocker)| |`clearOnRevocation`|`ClearOnRevocationConfig`|None|Cookies and storage keys to remove when a category is withdrawn| |`reloadOnConsentRevoked`|`boolean`|`true`|Reloads the page after a save turns off a category that was allowed| |`storageConfig`|`StorageConfig`|`{ storageKey: 'c15t' }`|Where the choice is stored| `storageConfig` takes `storageKey`, the cookie and localStorage name, `crossSubdomain` to share the cookie across subdomains, `defaultDomain` to set the cookie domain yourself, and `defaultExpiryDays`, which defaults to a year. The server reads the same cookie name, so set it here and not only in the browser. ## Appearance and copy |Option|Type|Default|Effect| |--|--|--|--| |`theme`|`Theme`|Stock tokens|Tokens rendered on the server into `