Where do you work now that you're not at-will? In the US, the vast majority of software/tech jobs are at-will; the exceptions are unionized shops (not common in tech) and people who have personal contracts (also not common except for senior executives). So presumably you're not in the USA?
Here's the questions I think you should ask yourself:
1. How likely am I to lose the new job? Is the employer stable (both financially and also in the sense of making rational decisions)? And related: how much more stable is your current job, really?
2. If I were to lose the new job, how hard will it be to find another one, and how similar/appealing will the new job be? If you're in a hot market and getting constant recruiter outreach, or if your current company would be happy to have you come back, then risk is low.
In addition, of course, you should balance the full package of alternatives; not just salary, but also career direction, personal growth, happiness, etc.