PrimerBench
PCR primer pairs ranked by nearest-neighbor Tm, with hairpin and dimer checks.
Paste a DNA sequence or FASTA record and instantly see its composition, reverse complement, translations in all six reading frames, open reading frames, and motif matches.
Free, no sign-up, and installable on your phone. Runs in your browser at seqbench.gataca.com.

Yes. SeqBench is free to use with no account or sign-up.
Short sequences (under 14 bases) use the Wallace rule; longer ones use a GC-based formula. For primer Tm with salt correction, use PrimerBench.
Analysis works on sequences of any practical length; the colored sequence view shows the first 20,000 bases to keep the page fast.
We build custom versions and full pipelines for research teams.