Bithumb review: a low-fee Korean exchange with a record AML fine, a 620,000 BTC ledger error and domestic-only access.

Bithumb says it keeps customer assets in offline cold wallets at a ratio above the statutory minimum and uses MPC-based signing with multi-person approval (company-reported); Korean rules require at least 80% of assets in cold storage (Block Media). Block Media also describes a design with one cold wallet and one hot wallet per asset, where deposits go straight to cold storage and the hot wallet is used only for withdrawals. It holds ISMS-P certification (first reported in February 2023). Those are real positives, but the record is poor. Bithumb suffered four reported security incidents between 2017 and 2019: about $7 million in February 2017 (reported), a staff-computer compromise in July 2017 that exposed data on roughly 30,000 customers and led to follow-on scam thefts, about 35 billion won (around $31 million) from hot wallets in June 2018, and a March 2019 loss of about $13 million that Bithumb described as an insider incident (Wikipedia puts it near $20 million, so the figure conflicts). Bithumb compensated customers each time, and customer cold wallets were reported unaffected in 2019. The decisive event came on February 6, 2026: during a promotion, an employee entered the payout unit as BTC instead of won and credited 249 winners with 620,000 BTC, about 15 times the roughly 40,000 BTC the exchange held. Some recipients sold, the Bitcoin price on Bithumb briefly fell to about 81.1 million won, and Bithumb recovered 99.7%, with about 125 BTC left unrecovered, and said it reimbursed the portion already sold from corporate reserves and compensated customers who sold at low prices. The regulator’s inspection reportedly also covers two similar earlier payout incidents. Customers were made whole, but the ledger showed balances that no reserve could have covered, and we found no independent proof-of-reserves programme. A single outlet also reported 13-hour altcoin withdrawal delays in August 2026 that the Financial Supervisory Service was reviewing; we could not confirm that elsewhere.

Bithumb is a domestic Korean exchange regulated by the Financial Services Commission and its Financial Intelligence Unit, and it operates a won market through a real-name bank account at KB Kookmin Bank (SpotedCrypto; the partner changed from NH Nonghyup in March 2025). Its enforcement record is the heaviest in this series for AML. On March 16, 2026 the FIU announced a 36.8 billion won fine (about $24 million), described as the largest ever imposed on a Korean crypto exchange, plus a six-month partial suspension of external transfers for new customers from March 27 to September 26, a reprimand for the CEO and a six-month suspension for the reporting officer. The FIU found about 6.65 million violations, including 45,772 transfers with 18 unregistered overseas operators. The Seoul Administrative Court later stayed the suspension pending a final ruling, so the practical impact was limited, and we could not confirm the final outcome of Bithumb’s legal challenge or whether the fine has been settled. Separately, authorities fined Bithumb about $136,000 in June 2026 for sending user data overseas in breach of privacy rules, and the Financial Supervisory Service opened a formal investigation after the February error. Ownership has also been a long-running question: Bithumb Holdings owns about 73.56% of Bithumb, KOSDAQ-listed Bucket Studio reaches about 30% of the holding company through Vidente, a person alleged to be its real owner has faced embezzlement charges, and a sale of Bucket Studio was delayed. Kiwoom Securities was reported in June 2026 to be negotiating a stake, with no terms agreed.

Fees are Bithumb’s strongest point, although sources disagree on the headline rate. Asia Economy reported that from February 5, 2024 Bithumb applied a flat 0.04% to all assets on its won market, down from 0.25% and below Upbit’s 0.05%. CoinMarketCap lists 0.04% maker and taker on the won market and free trading on the BTC market. SpotedCrypto and an August 2026 Asia Economy article instead describe 0.04% as the rate with a coupon, and SpotedCrypto cites a 0.25% standard rate; we could not reconcile these, so we treat 0.04% as the likely effective rate and 0.25% as possible without a coupon. Bithumb ran a zero-fee campaign from October 2023 to February 2024 that lifted its market share sharply, and rivals are cutting again: Coinone moved to 0.04% on August 3, 2026 and Korbit announced zero fees on its won market for a year from August 24. Withdrawal costs are modest (SpotedCrypto lists 0.001 BTC for BTC and 1,000 won for won), but a lower fee does not guarantee a better price, because Upbit’s deeper liquidity can produce tighter spreads. We could not load Bithumb’s live fee page, so confirm current rates before trading.

Bithumb is a spot-only venue. Coin counts depend on source: SpotedCrypto’s Q4 2025 comparison says 200+, its April 2026 comparison says 448, and CoinMarketCap says more than 440, so we treat it as roughly 200 to 450 depending on how listings and markets are counted. Staking is offered, and there are won, BTC and stablecoin markets; Bithumb held about 31% of Korean stablecoin trading value in June 2026 according to 4Pillars. We found no futures, margin or perpetuals, which is normal for a domestic Korean exchange, and no stock or ETF access. Coverage is broad for altcoins but narrow for products.

We found no reliable independent app-store or consumer rating for Bithumb, so this score rests on structure and reported features rather than a review average. The service is built for Korean residents: sign-up for the won market needs a Korean real-name bank account, and the interface and support are Korean-language first; we could not confirm how foreign residents are onboarded. Bithumb runs a customer lounge in Seoul’s Gangnam district, and the mid-2026 withdrawal-delay report and the February incident show that reliability under stress is a concern. Access for anyone outside Korea is limited.

Bithumb says its customer centre runs 24 hours a day by phone, chat and online board, plus walk-in support, and that it handled about 10.48 million inquiries in 2025 with a 98.0% response rate (company-reported). Earlier company figures put complaint resolution at 94.3% in the first half of 2022 and 98.3% in the first half of 2023. In August 2026 it became the first domestic exchange to add real-time voice-to-text on phone support. After the February incident it announced compensation for affected customers, including paying customers who sold at low prices. We found no independent customer-satisfaction ratings, and because these are company statistics we weight them moderately.

The extras are modest. Bithumb offers staking, a coupon system for fees, and a customer lounge, and it is pursuing the first stock-market listing of a Korean exchange: on August 3, 2026 it said it would finish internal readiness work in 2026, seek a preliminary listing review in 2027 and complete an IPO in 2028, after earlier plans for a Nasdaq listing in 2026 slipped. A shareholder noted it has paid dividends only once. Revenue is under pressure, with Upbit and Bithumb both reporting roughly 50% lower first-half 2026 revenue (The Block). We found no exchange token or launchpad.