What Upstairs does

Upstairs Inc. (주식회사 업스테어스) is a South Korea-based for-profit company that has operated since April 2018 as a specialized B2B marketplace for used mobile phones. The company addresses structural inefficiency in the Korean used phone distribution market — characterized by rapid price volatility, fragmented pricing information, and lack of an integrated platform — through a vertically integrated product suite. Core offerings include FonGabi (consumer-facing price information and multi-quote comparison for buying/selling used phones), Joongabi (dealer price comparison), Joongabi Manager (desktop and Android inventory management covering procurement through settlement), and Joongabi Pro (professional tier). The newer product surface includes Stock Master AI (launched June 2025, AI-assisted price forecasting for dealer inventory) and Treadit (2025 loyalty/rewards). Technology is a cloud-based platform (AWS) with web and API server architecture using Node.js, Vue.js, Nuxt.js, Express.js, MariaDB/MySQL, and MongoDB with Git/Jenkins CI/CD.

Upstairs monetizes through marketplace commissions on B2B transactions, subscription fees for Joongabi Manager (PC and mobile), freemium/quote-based pricing on FonGabi for consumers, and enterprise/managed service contracts (exemplified by the May 2024 supply agreement with KT Corporation). Distribution is hybrid: self-serve digital platforms (web, Google Play mobile apps) target long-tail SMB used phone dealers and individual consumers, while direct enterprise sales pursue telecom and large institutional clients. Marketing is concentrated in Naver Blog content, Instagram, and KakaoTalk channels. The company holds ISMS-KISA-2025-067z and Trusted Used Phone Transaction Provider (AC-20250623-A0002) certifications, supports both Korean-language user interfaces, and serves customers primarily in South Korea with emerging export activity (evidenced by $2M and $5M+ Export Tower Awards in 2023 and 2024 respectively).

Name

Upstairs

Legal name

주식회사 업스테어스

Website

https://upstairscorp.com

Company type

Private

Founded year

2018

Operating status

Operating

Short description

Upstairs (주식회사 업스테어스) is a South Korea-based B2B marketplace for used mobile phones, operating price comparison (FonGabi, Joongabi), inventory management (Joongabi Manager), and AI forecasting (Stock Master AI) products for dealers, consumers, and enterprise telecom clients.

Ownership category

akta.pro rank

Product category

Used Mobile Phone B2B Marketplace

NAICS

Electronics and Appliance Retailers (4492)

SIC

Wholesale-Electrical Appliances, Tv & Radio Sets (5064)

akta.pro primary industry

B2B Marketplaces & Wholesale Platforms (BPAMAGAD)

Keywords

• Used phone marketplace
• B2B price comparison
• Inventory management software
• Refurbished mobile trading
• Consumer electronics resale

Headquarters

HQ city

Mapo

HQ country

South Korea

HQ region

Asia

Offices1 record

Markets served

GTM type

B2B

Offering type

Digital Commerce or Content

Cost components

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

Revenue model

1. B2B Marketplace Transaction Fees: Upstairs operates a B2B marketplace for used phone trading. The platform likely generates revenue through transaction fees or commissions on trades facilitated between dealers.
2. Software Subscription (중가비 PC Manager/Mobile): Joongabi Manager (PC and Mobile) is a paid inventory management tool for used phone dealers, likely offered on a subscription basis.
3. Price Information Services: FonGabi and Joongabi provide used phone price comparison services, potentially monetized through premium subscriptions or B2B data licensing to dealers.
4. Enterprise/B2B Solutions: Supply solution contracts with enterprise partners such as KT for used phone supply solutions.

Pricing tiers

Go-to-market motion2 records

Distribution channels3 records

Marketing channels5 records

Core offering

Upstairs operates a specialized B2B marketplace for used mobile phones in South Korea, aggregating dealers and individual sellers on a single transaction platform. The company offers price comparison services (FonGabi and Joongabi), inventory management software (Joongabi Manager PC and Mobile), an AI-powered stock forecasting tool (Stock Master AI), and a professional tier service (Joongabi Pro) for used phone dealers.

Product overview

Upstairs operates a platform-plus-modules architecture for the used phone B2B marketplace. The core offering consists of 폰가비 (Fongabi), a consumer-facing multi-quote comparison service for buying and selling used phones, and 중가비 (Joongabi), a price comparison platform for dealers. These are supported by inventory management tools including 중가비 PC 매니저 (desktop program) and 중가비 모바일 (mobile app), plus 중가비 프로 for professional dealers. Newer additions include Stock Master AI (AI-powered price prediction) and 트레딧 (loyalty system), extending the platform's intelligence and engagement capabilities.

Differentiator

Problem solved

Functional benefit

Brands

• Fongabi (폰가비): Used phone price information service that provides real-time market prices and multiple quotes for buying and selling used phones
• Joongabi (중가비)
• Joongabi Manager (중가비 매니저)
• Joongabi Pro (중가비 프로)
• Stock Master AI
• Tread-it (트레딧)

Products and services

• FonGabi (폰가비) Consumer-facing used phone buy/sell service that provides multiple quotes and price comparison from trusted professional dealers, enabling transparent transactions between sellers and buyers of used mobile phones.
• Joongabi (중가비) Used phone price comparison web service for B2B dealers that aggregates pricing data from multiple vendors to help dealers find optimal prices when sourcing or selling used phones.
• Joongabi Manager PC (중가비 매니저 PC) Desktop-based inventory management program for used phone dealers that covers the full cycle from purchase to settlement, enabling efficient information management across procurement and sales workflows.
• Joongabi Manager Mobile (중가비 매니저 모바일) Mobile-optimized Android version of the Joongabi PC Manager inventory management program, designed for the mobility needs of used phone dealer business owners with core inventory features adapted for smartphones.
• Joongabi Pro (중가비 프로) Professional tier version of the Joongabi price comparison service with advanced features targeted at serious used phone dealers requiring deeper market insights and tools.
• Stock Master AI AI-powered stock price prediction and analytics tool for used phone inventory management, providing price forecasting capabilities to support dealer purchasing and stocking decisions on the B2B marketplace.
• Treadit (트레딧) Loyalty and rewards system for the used phone trading platform, designed to enhance user engagement and retention among marketplace participants.

Quantifiable outcome

• ₩5 million+ export award (2024)
• +1 more outcomes

Named customers3 records

Segments3 records

Ideal customer profiles3 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

AI capability1 record

Feature8 records

Partnerships

Four partnerships are on record, tiered core, minor and moderate.

• KT CorporationcoreStrategic or Co-development Partner · 1 May 2024Upstairs entered into a used phone supply solution supply contract with KT Corporation in May 2024. KT uses Upstairs' B2B marketplace platform and supply chain solutions for used phone procurement.
• BIRD Program Phase 2minorOthers · 1 January 2024Upstairs was selected for BIRD Program Phase 2 R&D support by the Small and Medium Business Technology Innovation Promotion Agency in November 2024.
• POST TIPS ProgrammoderateOthers · 1 January 2023Upstairs was selected for the POST TIPS support program in May 2023, a follow-on private investment-driven technology startup support program administered by the Korea Angel Investment Association.
• TIPS Program (민간투자주도형 기술창업지원사업)moderateOthers · 1 January 2018Upstairs was selected for the TIPS (Tech Incubator Program for Startups) program in November 2018, a government-backed incubation program driven by private investment. This provided access to funding, mentorship, and startup infrastructure.

Scale indicators3 records

Recent moves6 records

Expansion highlights6 records

Direct peers

• SellCell: SellCell is a price comparison aggregator for used smartphones and tablets, comparing buyback offers across multiple vendors. It is directly comparable to Upstairs' FonGabi multi-quote comparison service in functionality and target use case.
• Swappa: Swappa is a peer-to-peer marketplace for used smartphones with price guidance and listing controls. It is a direct functional peer to Upstairs' marketplace layer but skews B2C rather than B2B.
• ReCellular: ReCellular is a B2B used mobile device refurbishment and resale operator, handling device trade-in, grading, and wholesale redistribution. Comparable to Upstairs' B2B marketplace and KT enterprise supply operations from a supply-chain perspective.
• ItsWorthMore: ItsWorthMore is a B2B buyer of used phones and electronics offering instant quotes and bulk purchasing from dealers and carriers. Closely aligned with Upstairs' dealer-facing marketplace and inventory management value proposition.
• BankMyCell: BankMyCell provides side-by-side trade-in price comparisons for used smartphones across multiple buyback vendors. It mirrors FonGabi's core price-comparison mechanic and serves overlapping consumer and SMB use cases.

Broad incumbents

• Back Market: Back Market operates a global refurbished electronics marketplace spanning phones, laptops, and tablets. It is a broader recommerce incumbent that competes for the same end-customer demand that flows through Upstairs' B2B platform.
• Gazelle: Gazelle is an established US used electronics recommerce platform (owned by ReCommerce Holdings) that buys and resells used phones. It is a broader incumbent in the same recommerce category as Upstairs' marketplace.
• ecoATM: ecoATM operates a national kiosk-based buyback network for used phones and electronics in the US. While channel is different (kiosk vs. marketplace), it competes for the same upstream supply of used devices that feeds B2B redistribution.

Regional players

• Cashify: Cashify is India's largest used phone recommerce marketplace with both B2C and B2B dealer flows. It is a regional peer operating a similar vertically integrated used device marketplace model in a different geography.

Emerging players

• Phonecheck: Phonecheck provides device diagnostics, grading, and certification for the secondary mobile market. It addresses the trust and quality-verification layer that complements B2B used phone marketplaces like Upstairs' certified trading operations.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights6 records

Customer concentration

• Instagraminstagram.com/fongabi_official

Compliance2 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles1 record

Funding overview

Funding rounds4 records

Investors7 records

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 Upstairs