Prediki

What it is

A prediction market built like a wiki. Anybody may post a question, and anybody else may then rewrite its title, propose a better judgement rule, add answer options, write the background article, or propose the final result — each change going through a support-and-vote procedure with a 72-hour window rather than through a moderator. The market is the part that scores you; the editing is the part that makes it unusual.

Trading is in Credits, a free virtual currency, with nothing to deposit and nothing to withdraw. You invest Credits for or against an answer, and the price moves immediately as a result — there is no order book and no counterparty to find, so a thin question still has a price. Prices across the answers of a question are normalised to sum to 100%, which is what makes the multi-band numeric questions readable: an S&P 500 question on the site carries six ranges pricing out to 1.9%, 2.0%, 11.2%, 71.6%, 9.6% and 3.7%.

The record you build is expertise points, awarded per question and consolidated per topic, so the platform's claim is not "here is your Brier score" but "here is the topic you are actually good at". Questions with a larger incentive award more points. There is no published scoring formula, no calibration chart and no Brier or log score anywhere on the site.

Money reaches forecasters through Incentives: a sponsor pays a sum in advance, the incentive runs for a defined period, and at settlement it is apportioned among the traders — the better and earlier the prediction relative to other traders, the larger the share. Prediki's own help pages describe the mechanism in exactly those words and nowhere quantify it.

Availability

Open worldwide, free to join, no identity check and nothing to deposit. The terms require you to be at least 18 and legally capable of entering a contract, and Prediki reserves the right to refuse, suspend or terminate access at its sole discretion. Nothing in the terms singles out a country.

The operator is Prediki Prediction Markets GmbH, an Austrian limited liability company registered at the Commercial Court of Vienna on 30 December 2011, with contact addresses in Vienna, Kiel and San Francisco. The interface runs in English, German, Russian and Chinese, and the terms name both prediki.com and prediki.de as the site.

Pricing

Two products on one platform, and only one of them is what this card is about. Public prediction markets are free with unlimited users. Confidential questions — visible only to users the owner invites, under a non-disclosure agreement — are the paid tier: Essentials at USD 10 a month for up to ten users and at most ten concurrent confidential questions, and Professional priced per participant per month at USD 5 for 11 to 100 users, USD 4 for 101 to 200, USD 3 for 201 to 500 and USD 2.50 above 500, capped at a hundred concurrent confidential questions. Academic institutions get 50% off, non-profits 90%, and annual prepayment buys two months.

There is no trading fee and no cost to a forecaster at all. Recruiting a crowd, consulting and training are quoted separately.

Markets & resolution

Topics are whatever users have written, and the topic tree is correspondingly long-tailed — politics, macroeconomics and elections next to boxing, motorsport, astronomy and the Russo-Ukrainian war. The public questions open on 19 September 2026 were a university course market: a set of S&P 500, WTI crude and college-football questions tagged WFU PM Fall 2026 and owned by a named academic, with 41 to 52 transactions each and a few hundred views.

Resolution starts with the question owner, who is prompted automatically when a question falls due and enters the final result against the judgement rule on the page — the S&P 500 question names a specific quote page and the exact reference moment, 18 September 2026 at 16:00 EDT. The interesting half is what happens when the owner does not turn up. Prediki marks the question Publication is overdue, and any user may then propose the result themselves; a proposal needs one supporter to open a 72-hour vote, votes are weighted pro rata to capital invested in the question, and a vote against must be explained in a written comment. That is a genuine answer to the author-resolution problem, and this catalogue has not found another platform that implements one.

The regulations also require that a result be empirically observable and measurable, that answer options be exclusive and exhaustive, and that a modification never alter a question's substance.

Integrations

There are none. No API, no webhook, no export button, no first-party client, and nothing in the help pages that addresses automation. What you can take instead is the licence: user-contributed content on public questions is published under CC BY-SA 3.0, which is a more permissive position on reuse than any other platform in this category takes — Good Judgment Open forbids automated extraction outright and Hypermind's panel rules treat live prices as confidential. Prediki gives you permission and no mechanism.

Limitations

Liveness is the thing to check before you invest a season here. The site works, the price charts update and questions settle, but the footer copyright ends at 2022, the charting library is Highstock 1.3.2, and the only public questions open in September 2026 came from one university course. Several help articles — Credits, Price, Real-money distribution — are empty stubs reading "Please start an article". This is a maintained platform rather than a developed one.

The scoring is opaque. Expertise points are described but not defined, incentive shares are described as depending on how early and how precise your prediction was without a formula, and nothing on the site produces a number you could put in front of a research audience the way a Brier or log score travels.

Editability cuts both ways. A question you traded can be rewritten by other users, subject to a vote, and Prediki's own legal page says content is not subject to editorial supervision and that virtually all of it can be modified by anyone at any time.

And the incentive economy depends entirely on sponsors showing up. No sponsor, no money, and the questions open today carry none.

Alternatives

Manifold is the same "anyone writes the question" idea with far more traffic, a play currency, and the author rather than a vote deciding the result. Metaculus if you want staff-written questions and a scoring rule you can cite. Hypermind if the contest prize is the point, though its questions are written for sponsors rather than by you.