(3S,4S)-Tofacitinib (Tofacitinib Impurity C) is a less active enantiomer of Tofacitinib (tasocitinib; CP-690550; Xeljanz), which is an inhibitor of JAK3 (Janus-Associated kinase) and an FDA approved drug for the treatment of rheumatoid arthritis (RA), psoriatic arthritis, and ulcerative colitis.

NVP-BSK805 is a novel, potent and selective ATP-competitive JAK2 inhibitor with IC50s of 0.48 nM, 31.63 nM, 18.68 nM, and 10.76 nM for JAK2 JH1 (JAK homology 1), JAK1 JH1, JAK3 JH1, and TYK2 JH1, respectively.

Tofacitinib citrate (formerly CP-690550 citrate), the citrate salt of tofacitinib (tasocitinib or CP 690550, brand Xeljanz), is a novel, potent and orally bioavailable inhibitor of JAK3 (Janus-Associated kinase) with IC50 of 1 nM in cell-free assays.

Ruxolitinib sulfate, the sulfate salt of ruxolitinib which is also known as Jakafi, Jakavi, INC-424, INCB-18424 or INCB-018424, is the first-in class, potent, selective, and orally bioavailable JAK1/2 (Janus-associated kinase) inhibitor with IC50 of 3.3 nM/2.8 nM in cell-free assays, it exhibits >130-fold selectivity for JAK1/2 versus JAK3.

ZM 39923 HCl, the hydrochloride salt of ZM-39923, is a novel and potent inhibitor of Janus kinase-JAK1/3 with potential anti-inflammatory activity.

JAK1-IN-4 is a novel and potent JAK1-selective kinase inhibitor with immunomodulatory effects.

Cerdulatinib HCl (formerly PRT2070; PRT062070) is a novel, potent, selective orally bioactive, and multi-targeted tyrosine kinase inhibitor of JAK1/2/3/TYK2 and Syk with potential antitumor activity.

Delgocitinib (formerly LEO-124249; JTE052; LEO124249; JTE-052; Corectim) is a potent and selective JAK inhibitor with anti-inflammatory activities and has been approved in 2020 for use in Japan for the treatment of autoimmune disorders and hypersensitivity, including inflammatory skin conditions (e.g. atopic dermatitis).

AG-490 (also known as Tyrphostin B42; zinc-0255794) is a novel, potent and selective inhibitor of EGFR (epidermal growth factor receptor) with potential antitumor activities.

CEP33779 is a novel, potent, orally bioactive, highly selective inhibitor of JAK2 (Janus kinase) with potential antitumor and anti-inflammatory activity.