7 companies are listed as custom peptide synthesis companies in the United States. 2 hold active US Drug Master Files for peptide APIs, most often for Semaglutide, Bivalirudin, Cetrorelix. 2 have a regulator record of GMP manufacturing. 6 score High (90 or more).
Ordered by score. Scores follow the published rules and are not affected by paid placement. Updated 2026-11-13.
RK Pharma subsidiary offering API process R&D, custom synthesis and generic APIs, with US offices and plants in Gujarat and Andhra Pradesh. Holds US DMFs for 6 peptide APIs.
US peptide API CDMO with facilities in the US and China.
Fremont, California peptide maker founded in 1993, now a subsidiary of Kaneka Eurogentec, offering catalogue, custom and GMP-grade peptides and assay kits.
Texas custom synthesis company in business since 1984, making peptides, oligonucleotides and bioconjugates at its Lewisville facility.
Life-science services company with a large custom peptide synthesis service.
Thermo Scientific custom peptide service making research peptides of 2-110 amino acids by Fmoc solid-phase synthesis, plus peptide libraries and AQUA heavy peptides.
New Jersey contract research company founded in 2008 that makes custom peptides, peptide conjugates and PNAs, and also provides protein and antibody services.
7 companies. Each listing shows location, business model, documentation and a score from 0 to 100.
By score: Apicore LLC (RK Pharma) (98), AmbioPharm (95), AnaSpec (90), Bio-Synthesis Inc (90), GenScript (90). Scores measure checkable evidence, not product quality, and paid placement does not change them.
Apicore LLC (RK Pharma) and AmbioPharm hold active Type II DMFs for peptide APIs in FDA's DMF list. A DMF is a confidential file submitted to FDA; FDA does not approve DMFs, but drug applications can reference them.
Confirm the legal entity, ask for lot-specific certificates of analysis that the testing lab can verify, check FDA warning letters and import alerts, and for GMP material ask for regulator inspection records rather than marketing claims.