As a guide, entry-level software engineering salaries can range from S$3,000-6,000 in Singapore, with a median of around S$4,000. Mid-level software engineering salaries typically range between S$5,000-10,000, with a median of around S$6,000.
Software engineers usually enjoy stronger career trajectories at companies where software is core to the company's operations. Career trajectory will also depend on the company’s rate of growth, as well as individual performance. Just like other professions, software engineers get promoted quickly when they take initiative and value-add to their jobs.
Finally, a career switch to software engineering is highly possible at any age.
However, it may require some sacrifices if you are making the transition at a later stage of your career. This is due to relatively modest entry-level software engineer salaries, which start at ~S$3,000/month. These may be higher depending on the company, but one must still be prepared to start at an elementary level again nonetheless.