Compared
Two ways to answer, side by side.
Each of these compares two approaches rather than two vendors. Every line in every table is something this service can back with evidence, and where an approach cannot answer, the table says so.
All comparisons
SMTP verification vs. syntax validation
Syntax validation proves an address is well formed. SMTP verification proves a mail server will accept it. Only the second tells you mail will arrive.
Real-time vs. bulk verification
The same checks and the same four verdicts, in two shapes. Real-time answers one address while somebody waits; bulk works through a list you already have.
Verification vs. list hygiene
Verification is a fact about an address at a moment. List hygiene is a practice about engagement over time. Neither substitutes for the other.
Run one and see the difference.
The free checker returns the whole result — every stage, every reason code, nothing held back.