Mathew Joseph

I help founders move beyond referral-only pipeline by building a repeatable outbound system their team owns and runs.

LondonLinkedIn

GTM engineer since 2024: outbound systems for B2B teams as a freelancer, then for RevenueFlow's clients. Since June 2025, as GTM engineer at Cerebrium, a YC-backed AI infrastructure company, I have built its go-to-market system from nothing: enrichment and qualification in Clay, HubSpot beneath it and the outbound on top. Its CEO has publicly cited a 35% LinkedIn reply rate against a 2-4% norm.

25/25

Clay Solutions Partner exam

Mathew's number

$100K

new MRR into pipeline, per CEO

Mathew's number

55%

LinkedIn reply rate vs 2-4% norm

Mathew's number

Work

Reviewed inside a cohort where it says so. Numbers are the student's.
Case study
Cerebrium, embedded GTM engineer, since June 2025
An outbound pipeline from sources to CRM
Pulls potential customers from several sources, screens them against the company's own criteria in Clay, enriches the ones that qualify and routes them into HubSpot. It replaced prospecting by hand; the commercial team has run on it since 2025. Tradeoff: cheap screening runs before paid enrichment. Broad filters give a weaker signal, but no company that gets rejected costs an enrichment.
Case study
Cerebrium, 2026, outside my assigned role
Cerebrium's official agent toolkit for AI coding assistants
Developers ask AI coding assistants to set up their deployments, and leave quietly when it breaks. I proved with a reproducible test that the file those assistants read failed its own spec, then specified, directed and shipped the fix and an official toolkit, executing through an AI coding agent. Tradeoff: directing an agent made it fast, so a second reviewer approved every change before merge.
Case study
Cerebrium, July 2025 to April 2026
A reply standard that became an automated classifier
In my third week I wrote the standard for answering interested prospects: answer directly, give one piece of proof, offer a low-friction next step. When volume outgrew human reading, I designed a classifier that checks each conversation against the ICP and records every decision. Tradeoff: it reads the whole thread, not reply 1, at extra cost, as a contact can sound keen and then close the door.
Case study
Cerebrium, August to September 2025
A lead-source model, tested and reversed
One practitioner's LinkedIn audience was converting to meetings noticeably better than the rest, and nobody knew why. I turned it into a model of what makes a source worth monitoring, and set up a record linking meetings to their source campaign. Within a month it showed my top-ranked source had booked none, so I reversed the model. Tradeoff: a model can fail where a list cannot; I chose that.
Case study
Cerebrium, January 2026
One version-controlled source of truth for GTM
With two separately built GTM frameworks in play, I moved 100+ GTM documents into version control in one operation, added a source-of-truth register and an append-only decision log, then merged both frameworks into one customer definition. Tradeoff: I accepted a reversal of my own design, screening on company data before the costly signal work, because screening cheaply first was better.

Skill map

0 Clay use cases proven, 6 shared. Tap or hover one to see the proof and what it is built from.
Proof levelsCertified by ClayVerified workShared, in review
Phase 1

Crawl

Clean, scored data you can trust

0 proven, 2 shared
Phase 2

Walk

Automations that run without you

0 proven, 2 shared
Phase 3

Run

Signals and reps working the same system

0 proven, 2 shared

Data foundation

Reachable accounts and contacts, lower tool spend

Crawl

Grow pipeline

Outreach volume, reply rate and speed to lead

Walk
Run

Building blocks

0 proven. The Clay skills every use case is made of. Tap or hover a use case to see its recipe.

Sourcing0Where records come from
Enrichment0What you learn about them
Logic0What you decide
Activation0Where the decision lands
Operate0Why it keeps working

Credentials

Issued by Clay. Anyone can verify the ID.

Clay Certified, Outbound Automation · in progress

Vantis: Outbound Automation
15% complete

Teams I've built for

Credentials and badges are issued by Clay. Mathew can hide them, not edit them.