Flink
Create QR Codes, embeddable link previews for your website and crawls/scrapes metadata. (Demo) MIT Docker
Complete e-mail solution with IMAP4, SMTP, SPF, DKIM, DMARC, MTA-STS, DANE and DNSSEC, reputation-based and content-based junk filtering, Internationalization (IDNA), automatic TLS with ACME and Let’s Encrypt, account autoconfiguration, and webmail. (Source Code) MIT Go