flutter_prerender library

Prerender a Flutter web app to static, crawlable HTML for SEO.

The public API is split into small, independently testable pieces:

Most users invoke the bundled flutter_prerender command rather than the library directly; see runCli.

Classes

CapturedPage
The raw material recovered from one loaded route: the document title, the serialised Flutter semantics DOM, and the app's rendered text.
ContentNode
A single piece of crawlable content recovered from a Flutter semantics tree.
FailedRoute
A route whose capture failed outright, for example a same-origin link to a PDF, an image, or some other non-Flutter asset that a crawl reached.
HeadingContent
A heading recovered from the semantics tree (<h1> .. <h6>).
HtmlBuilder
Serialises recovered ContentNodes and RouteMeta into a complete, static, crawlable HTML document.
ImageContent
An image recovered from the semantics tree, carrying its alternative text.
LinkContent
A hyperlink recovered from the semantics tree (<a href>).
PageCapturer
Loads a route in a real browser and captures its content.
ParagraphContent
A block of body text recovered from the semantics tree (<p>).
ParityGuard
Compares prerendered body text against the text a Flutter app renders and reports any divergence.
ParityReport
The result of comparing the prerendered text against Flutter's own accessibility text.
PrerenderConfig
The fully resolved configuration for a prerender run.
PrerenderEngine
Drives the end-to-end prerender: capture each route, recover content, build HTML, run the parity guard, write files, and emit a sitemap.
PrerenderResult
The outcome of a complete prerender run.
PuppeteerCapturer
A PageCapturer backed by package:puppeteer and headless Chrome.
RouteMeta
SEO metadata for a single prerendered route.
RouteResult
The outcome of prerendering a single route.
RouteSpec
A route to prerender together with its per-route SEO metadata.
SemanticsExtractor
Recovers an ordered list of ContentNodes from the HTML of a Flutter semantics tree (<flt-semantics-host> and its descendants).
SitemapEntry
A single <url> entry in a sitemap.
StaticServer
A minimal static file server used to serve a flutter build web directory to the headless browser during prerendering.

Constants

defaultConfigFile → const String
The default config file name looked up in the working directory.
packageVersion → const String
The published version of the package. Kept in sync with pubspec.yaml.

Functions

buildParser() → ArgParser
Builds the command-line argument parser for the tool.
buildRobotsTxt({String? sitemapUrl}) → String
Builds a robots.txt that allows crawling and, when sitemapUrl is given, points crawlers at the sitemap.
buildSitemap(Iterable<SitemapEntry> entries) → String
Builds a sitemap.xml document from entries.
contentTypeFor(String filePath) → String
Returns the MIME type for filePath based on its extension, defaulting to application/octet-stream.
discoverRoutes(Iterable<String> hrefs, {required Set<String> known, required int limit, String? origin}) → List<String>
Selects new same-origin routes discovered from a page's link hrefs.
joinUrl(String baseUrl, String path) → String
Joins a site baseUrl and a route path into a single absolute URL, collapsing the slash between them.
normalizeRoute(String raw, {int? lineNumber}) → String
Normalises a single route path.
parseRoutesFile(String content) → List<String>
Parses the contents of a plain-text routes file into normalised route paths.
resolveWithinRoot(String rootDir, String requestPath) → String?
Resolves requestPath against rootDir, returning an absolute file path, or null if the path would escape rootDir (a traversal attempt).
runCli(List<String> args, {StringSink? out, StringSink? err, PageCapturer capturerFactory(PrerenderConfig config)?}) → Future<int>
Parses args, runs the prerender, and returns a process exit code.
sameOriginRoute(String href, {String? origin}) → String?
Resolves a discovered link href to a same-origin route path, or returns null when the link is not a crawlable page on this site.

Exceptions / Errors

BrowserLaunchException
Thrown when the headless browser cannot be launched (for example, when no Chrome/Chromium executable can be found or downloaded).
BuildNotFoundException
Thrown when the Flutter web build directory is missing or incomplete.
ConfigException
Thrown when a configuration file or route list cannot be parsed.
PrerenderException
Base class for all errors thrown by flutter_prerender.
RouteCaptureException
Thrown when a route cannot be captured, for example when the page never produces a Flutter semantics tree within the configured timeout.