Flowchart makerfrom plain language, free.

flowchart TD
  start([User opens the login page]) --> form[/Enter email and password/]
  form --> locked{Account locked?}
  locked -- Yes --> lockMsg[Show locked message]
  locked -- No --> check{Password correct?}
  check -- Yes --> reset[Reset failed attempts]
  reset --> session[Create session]
  session --> dashboard([Open the dashboard])
  check -- No --> count[Add one failed attempt]
  count --> limit{Three failed attempts?}
  limit -- No --> warn[Show attempts left]
  warn --> form
  limit -- Yes --> lock[Lock the account for 30 minutes]
  lock --> alert[Email a security alert]
  alert --> lockMsg
  lockMsg --> unlock[Email an unlock link]

  classDef ok fill:#dcfce7,stroke:#16a34a,color:#14532d
  classDef bad fill:#fee2e2,stroke:#dc2626,color:#7f1d1d
  class session,dashboard ok
  class lock,alert,lockMsg bad