What Underscore does

Underscore (legally Underscore Consulting LLP) is a privately held, Brighton-based consultancy founded in 2011 by Noel Welsh and Dave Gurnell that specializes in Scala and functional programming software development. The firm operates three integrated service lines: software development (data engineering, web and cloud services, distributed systems), consulting (code review via its Review & Improve service, mentoring engagements pairing client developers with Underscore experts), and instructor-led training (Essential Scala and Advanced Scala with Cats, delivered on-site for enterprise teams or as six-week online cohorts). Pricing is published globally in USD, GBP, and EUR, with private courses priced at $11,250 / £7,500 / €10,500 for up to 10 participants and payment due 14 days from invoice.

The firm monetizes through three revenue streams: training courses (structured multi-week or multi-day programs with bundled books), professional services consulting (project-based development, code review, mentoring), and book sales (now largely free/open source as of 2017, with print copies available for purchase). Its customer base includes large enterprises across diverse verticals — Intel, BBC, HSBC, Verizon, Comcast, YOOX NET-A-PORTER, Goodlord, Nordstrom Rack, and BoomTown — alongside training testimonials from The Guardian and Stanford. The company maintains a horizontal segmentation approach rather than vertical specialization, and distributes through direct enterprise sales, a self-serve training booking portal, and an e-commerce book storefront.

Underscore's competitive positioning rests on rare, deep Scala expertise and a published content library (Essential Scala, Scala with Cats, Essential Slick, The Type Astronaut's Guide to Shapeless) that also functions as authoritative community reference material. The firm is active in the Scala ecosystem through conference participation (Scala Exchange, Scala Days), GitHub open-source contributions, a regular newsletter, and an active blog. The company remains privately held by its founders with no disclosed external investors, parent entities, or subsidiaries, and operates with a headcount band of 11–50 employees.

Name

Underscore

Legal name

Underscore Consulting LLP

Website

https://underscore.io

Company type

Private

Founded year

2011

Operating status

Operating

Headcount range

11–50 employees

Short description

Underscore is a private Brighton-based Scala and functional programming consultancy offering software development, consulting, and training services to global enterprises across financial services, telecom, media, and retail.

Ownership category

akta.pro rank

Headquarters

HQ city

London

HQ country

United Kingdom

HQ region

Europe

Offices5 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Technology or R&D, Marketing or Sales, Operations, Others

Revenue model

1. Training Courses: On-site private courses for teams (3 days) and online courses via live video conferencing (6 weeks). Also public training courses. Includes complementary books.
2. Consulting Services: Software development consultancy in Scala and functional programming, including code review, mentoring, and development services
3. Book Sales: Sale of technical books including Essential Scala, Scala with Cats, Essential Slick, and The Type Astronaut's Guide to Shapeless. Books were made free and open source around 2017.

Pricing tiers

Go-to-market motion1 record

Distribution channels3 records

Marketing channels6 records

Core offering

Underscore is a global Scala and functional programming consultancy that provides three interconnected service lines: software development (data engineering, web/cloud services, distributed systems), consulting (code review and developer mentoring), and training courses (on-site private and online live instructor-led Scala courses). They complement these services with published technical books including Essential Scala, Scala with Cats, Essential Slick, and The Type Astronaut's Guide to Shapeless that serve as course materials and standalone learning resources.

Product overview

Underscore is a global Scala and functional programming consultancy offering a portfolio of professional services and educational products. The core offering consists of three interconnected service lines: Software Development Services (data engineering, web/cloud services, distributed systems), Consulting Services (code review, mentoring), and Training Courses. The training division provides both on-site instructor-led courses and online programs, anchored by two flagship course brands: Essential Scala for experienced developers new to Scala, and Advanced Scala with Cats for developers learning advanced functional programming abstractions using the Cats library. Complementing the training are published books including Essential Scala, Scala with Cats, Essential Slick, and The Type Astronaut's Guide to Shapeless, which serve as course materials and standalone learning resources. The company operates primarily as a professional services firm rather than a software product company.

Differentiator

Problem solved

Functional benefit

Products and services

• Software Development Services Professional Scala and functional programming development services covering data engineering pipelines, scalable web and cloud services, and distributed/parallel computing systems. Built for enterprises that need expert Scala delivery capacity.
• Consulting Services (Code Review & Mentoring) Advisory services including the 'Review & Improve' code review service that combines review with practical advice for team assurance, and Mentoring programs that pair client developers with Underscore experts on an ongoing basis to accelerate delivery.
• Training Courses Instructor-led Scala and functional programming training delivered as on-site private 3-day courses, online 6-week live courses, and public training courses. Pricing is $11,250 / £7,500 / €10,500 for cohorts up to 10 participants.
• Essential Scala (Course) Flagship 3-day on-site or online training course covering Scala from basics to advanced problem-solving techniques, targeted at experienced developers with one or two years of OOP or functional programming experience taking first steps in Scala.
• Advanced Scala with Cats (Course) Advanced training course teaching key abstractions including monoids, functors, monads, monad transformers, and applicative functors using the Cats library. Designed for experienced Scala developers (about a year of experience) wanting to take next steps in engineering robust and scalable systems.
• Scala with Cats (Book) Published book covering the material taught in the Advanced Scala with Cats course, including exercises and case studies on system architecture and design using functional programming techniques. Made free and open source around 2017.
• Essential Slick (Book) Published guide to the Slick Scala library for relational database access, covering version 2.1 of the library with practical examples and exercises.
• The Type Astronaut's Guide to Shapeless Published book covering Shapeless, a Scala library for generic programming, authored by Underscore consultants.

Named customers11 records

Segments4 records

Ideal customer profiles2 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature7 records

Scale indicators1 record

Recent moves5 records

Expansion highlights4 records

Direct peers

• 47 Degrees: Pure-play functional programming consultancy specializing in Scala, with similar training, consulting, and open-source content offerings. Closest direct competitor in the Scala services market.
• Ziverge: Scala and functional programming consultancy offering development, training, and ZIO-based services. Direct overlap in target customers, technology stack, and service mix.
• SoftwareMill: Scala/Java consultancy offering development, consulting, and training services to enterprise clients. Competes for similar Scala engineering and data engineering engagements.
• Scalac: Scala and big data consultancy offering development, mentoring, and recruitment services. Closely comparable business model targeting enterprise Scala teams.
• VirtusLab: Scala consultancy with strong FP expertise, offering development, training, and open-source contributions. Direct peer in the European Scala services market.
• Cake Solutions: UK-based Scala and reactive systems consultancy with training, consulting, and development offerings. Highly comparable in geography, stack, and service mix.

Broad incumbents

• Lightbend: Commercial steward of the Scala/Akka ecosystem, offering enterprise platforms, support, and training. Larger incumbent that intersects with Underscore's training and consulting on Scala infrastructure.
• ThoughtWorks: Global technology consultancy with strong functional programming heritage (Scala, Clojure, Haskell). Competes for enterprise FP engagements at much larger scale.

Emerging players

• Codacy: Code quality and code review automation platform with strong Scala support. Adjacent to Underscore's code review consulting service but offers a software product rather than human-led review.
• Iterators Consulting: Scala and big data consultancy offering development, mentoring, and training services. Smaller peer with overlapping customer base and similar service mix.

Market position

Strengths4 records

Weaknesses4 records

Competitive moat4 records

Key risks6 records

Key highlights6 records

Customer concentration

• Xx.com/underscoreio
• GitHubgithub.com/underscoreio
• LinkedInlinkedin.com/company/underscore-consulting-llp

Revenue estimate

Valuation estimate

Number of profiles

Profiles3 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Underscore