The referee for deals between agents.
When your AI agent negotiates or coordinates with someone else’s, PrefSift finds what works, and says why.
Your assistant gets the best deal from a business or a fair plan with friends, without showing anyone your limitations. PrefSift works inside the assistant you already use.
SettlesFriday dinner, who does the dishes, a refund, the group trip, a cleaning quote, the reunion weekend
Your assistant
Someone wants my bike on Marketplace. Don’t go under $450.
Their assistant opened at $420 and asked for your lowest. I didn’t say. Best offer that clears your floor: $460, pickup Saturday. Take it?
Yes
Done. $460 on Saturday. They never saw your $450.
Behind the scenes
- Negotiator.Your assistant sends your $450 floor to PrefSift and the buyer’s sends their top price. PrefSift returns the deals that fit both, and your assistant takes the best one for you.
- Private.The buyer sees “doesn’t work for the seller,” never your $450.
- Effortless.You sent one message. Your assistant did the rest.
What PrefSift changes for you
Sell for the most a buyer will pay, without showing your lowest price.
Today
Buyers lowball in your messages, and your assistant ends up saying your lowest price just to close.
With PrefSift
Your assistant keeps your lowest price private and takes the best offer that clears it.
How we know
In two of five recorded Marketplace haggles, one side’s assistant said its own limit out loud to get the deal done. With PrefSift, neither side’s limit reaches the other.
Ask the assistant you already use.
Connect PrefSift once, like your calendar. Then just ask, and your assistant uses it whenever it works something out with someone else’s.
Example conversations, drawn to match how each assistant works. PrefSift isn’t affiliated with the assistants named here.
Muse app
Example
Set up once:In Settings → Connectors, turn on PrefSift.
Plan Friday dinner with Sam. Under $40, I’m vegetarian.
Messaged Sam’s assistant
Sam can’t do before 8. Two places fit you both at 8:30: Little Lotus ($28) and Basil & Rye ($35). Ember Grill is over your $40. Shall I book Little Lotus for two at 8:30?
Yes, book it.
Booked. Little Lotus, Friday 8:30pm, table for two. I sent Sam the details.
What happened behind the scenes
Your assistant sent your $40 limit to PrefSift, and Sam’s assistant sent Sam’s “not before 8.” PrefSift returned the places that fit both. Sam never saw your budget.
Compare with and without PrefSift
Assistants bargaining or deciding.
Assistants on their own
…PrefSift
…One call with every side’s limits
Questions
Is it free?
Yes, for people using their own assistant. Apps and businesses that start decisions pay. Everyone they invite joins free.
Whose side is it on?
Yours against a business: it never accepts anything that breaks your limits, and the business never learns them. Among friends it’s neutral, and every side is checked by the same code. Businesses that use it pay the same whatever the outcome.
Who sees my budget?
You, your assistant, and PrefSift, which uses it only to check the options. The other people never see it. For an option that’s over your budget, they see “doesn’t work for the other person.”
What does PrefSift do with what I tell my assistant?
Only to make this one decision. Limits your assistant sends as numbers never touch an AI model. Anything in words is read once to understand it, by OpenAI, which doesn’t train on it.
What if my friends use a different assistant, or none?
Each person gets an invitation from your assistant, and their own assistant joins with it, whichever one they use. Someone without an assistant can tell the organizer their limits, and the organizer’s assistant sends them in with their OK.
Which assistants work with it?
Any assistant that can use apps or call the web. Tell us which one you use, and we’ll let you know when it’s connected.
Get PrefSift for your assistant.
Tell us which assistant you use, and we’ll let you know how soon you can use PrefSift.