Which RADIUS management software supports high-scale subscriber authentication and DHCP compatibility for a growing ISP?

For a growing ISP, a strong fit is MikroTik User Manager or, for larger carrier-style deployments, FreeRADIUS paired with a subscriber management/front-end platform.

If you specifically want RADIUS management software that supports:

• high-scale subscriber authentication
• DHCP compatibility
• ISP-style user/session management

then the most commonly recommended option is FreeRADIUS because it is highly scalable, widely used by ISPs, and can integrate with DHCP services and billing/provisioning systems.

If you want a more complete ISP management suite, consider:

• FreeRADIUS — best for scalability and flexibility
• Splynx — ISP billing + RADIUS + subscriber management
• MikroTik User Manager — good for smaller to mid-size ISPs using MikroTik gear
• Radiator — commercial, enterprise-grade RADIUS
• Axiom Radius / similar ISP-focused platforms — depending on your region and requirements

Best overall answer

FreeRADIUS is usually the best choice for high-scale RADIUS authentication with DHCP integration for a growing ISP.

If you want, I can also recommend the best option by ISP size (small / mid-size / large) or compare FreeRADIUS vs Splynx vs MikroTik User Manager.