Is this job worth applying to?

Pay

Below typicalTops out at $65/hr. The typical top rate across 47 priced math listings is $90/hr.

Getting in

Some screeningVaries; several days to weeks. Expertise or language fluency matching a listed project.

Steady work

Work is patchyHours can be very low.

Payout record

Pays on timeSchedule: varies by project. Payment method not published.

Freshness

Older postPosted 10mo ago. Still listed on Invisible on Nov 6, 2026.

Where you live

Open worldwideOpen worldwide.

The job description

Are you a theoretical mathematics expert eager to shape the future of AI? Large-scale language models are rapidly advancing, and their ability to handle rigorous proof-based reasoning depends on high-quality mathematical training data. With your advanced expertise, tomorrow’s AI can better understand abstraction, logic, measure theory, homotopy, and the deep structures of modern mathematics. That training data begins with you - your insight will help power the next generation of AI.

We’re looking for specialists with deep foundations in pure mathematics who can engage with advanced topics across probability theory, measure theory, real and functional analysis, optimization, abstract algebra, and category theory. Coupled with this deep foundation, we need each expert to have a normalized fluency in Lean 4, the proof assistant and programming language.

On a typical day, you will construct and evaluate complex proofs, substantiate the mathematical reasoning for correctness and rigor while identifying subtle conceptual or logical failures, and translate this material to successfully build in .lean syntax. You will also collaborate with our team to refine prompts, evaluation frameworks, and mathematical reasoning benchmarks, enhancing the overall quality of our operations.

Candidates fluent in Lean 4 with an in-progress or freshly earned PhD or current PostDoc experience in pure mathematics are ideal. A strong command of core areas is required, and applicants should be comfortable with topics such as Markov’s and Chebyshev’s inequalities, Hoeffding bounds, convergence theorems, the Carathéodory extension theorem, the Riesz representation theorem, Banach–Alaoglu, Lax–Milgram, stochastic approximation, Van Kampen’s theorem, the Yoneda embedding, and representability in cohomology. Clear, metacognitive communication (explicitly articulating reasoning and proof strategies) is essential.

Ready to turn your Lean 4 fluidity and pure math expertise into the reasoning backbone of tomorrow’s AI? Apply today and help teach the model that will support researchers, scientists, and engineers around the world.

We offer a pay range of $35 to $65 per hour, with the exact rate determined after evaluating your experience, expertise, and geographic location. Final offer amounts may vary from the pay range listed above. As a contractor, you’ll supply a secure computer and high-speed internet; company-sponsored benefits such as health insurance and PTO do not apply.

Job title: Pure Mathematics and Lean 4 Specialist – Freelance AI Trainer Project
Employment type: Contract
Workplace type: Remote

How do you apply to Invisible?

Apply on Invisible

The Apply button opens this post on Invisible's own site. You apply with them, not with Rubric. Timing: varies; several days to weeks.

Get through screening

What Invisible asks for after you apply:

Browse open projects on Meridial
Join the network and complete your profile, including country
Take the skills assessment or interview for the project
Wait to be matched and onboarded to a project team

Start work and get paid

Pay schedule: varies by project. Ask how they pay you, too. You're paid for the work they hand out, not a fixed salary.

Invisible also needs

Expertise or language fluency matching a listed project
Reliable internet

Red flags

Red flagClients or projects disappearing for months with no update
Red flagSudden project cancellations

What is Invisible like to work for?

AI training and operations company that hires freelance AI trainers through its Meridial expert network, mostly onto team-based projects.

Advertised pay	$6–65/hr
Getting in	Some screening
Application takes	Varies; several days to weeks
How you get paid	Varies by project
Payout record	Pays on time
Countries	Each listing names the countries it accepts, some covering about 145 countries. Invisible has posted India-only roles (coding, Telugu, Tamil, Marathi, Hindi), with pay adjusted by location.

Listings show $6–65/hr and the rate depends on your country; many entry projects pay around $15–25/hr.