Links Checker

CLI tool that crawls a website and reports broken (4xx+) and moved (3xx) links. Made for checking a blog or static site before publishing.

• Java 25

mvn clean package

java -jar target/links-checker-0.0.1-SNAPSHOT.jar https://example.com/

Sample output:

I.Links : 2
Time: 0s | Links/s: 3.2

--- Queries per external host ---
iana.org: 1
example.com: 1
--- BAD LINKS ---

--- MOVED LINKS ---
https://iana.org/domains/example -> https://www.iana.org/domains/example

Progress symbols: I internal page, . external link OK, 4/5 external link failed with a 4xx/5xx, s skipped host.

Without an argument the tool prints usage and exits with code 1.

• Pages under the start URL are crawled; external links are checked but not crawled deeper.
• Links are fetched in parallel on virtual threads, grouped by host: a given host never sees more than one request at a time.
• Relative links are resolved against the page they appear on; fragments are stripped; only http(s) links are followed (no mailto:, javascript:, ...).

Defaults live in src/main/resources/application.yml:

To override without rebuilding, place an application.yml next to the jar (Spring Boot picks it up automatically).