Anyone Have Experience with Custom Peptide Synthesis Providers?

Hey all,
I’m currently looking into custom peptide synthesis for a project I’m running in the lab. It's a fairly complex sequence with a few unusual modifications, so I'm trying to find a provider that offers high purity and reliable turnaround times. I’ve seen a lot of options out there, but it’s kind of overwhelming trying to figure out which ones are consistent when it comes to both quality and delivery.

I’ve been coordinating peptide orders for an immunology project, and the main thing I’ve found is that consistent purity over multiple batches is a real challenge. A lot of providers advertise high specs but don’t always deliver the same quality from one synthesis to the next. So now I always ask if they’ve done similar sequences before and if they use in-house synthesis or outsource. That can really impact batch reliability.Also, storage and shipping conditions matter more than I thought—especially if your peptide is hydrophobic or easily degraded. I’ve started requesting documentation about how they handle lyophilization and stabilization. It’s a small thing, but in longer-term studies it can really affect results if the product degrades faster than expected.

We had a pretty specific need last quarter—multi-peptide sets with custom linkers—and ended up sourcing from a company listed on https://gentaur.co.uk. I was actually surprised by how much customization they allow through their system. They handled the specs for non-standard residues better than I expected, and we got purity levels above 95% without needing to request any rework. The communication wasn’t overly chatty, but they provided structured updates on the synthesis and shipment process. That helped manage expectations, especially because our project timeline was tight. One thing we noticed: it’s better to submit sequences with precise annotations for every modification, even the small ones. It avoids delays later in the quote or production stages.