At 13:45 UTC on November 27, 2010, a Bitcointalk user named slush posted a plan1. He had mined on three CPUs for a few weeks and had yet to find a block. “Join poor CPU miners to one cluster and increase their chance to find a block!” he wrote.
Behind the handle was Marek Palatinus. Trezor, the hardware wallet maker, now lists him as a co-founder12. His plan became pooled mining. Today, pools find almost every Bitcoin block. mempool.space lists 290 of the past year's 52,381 blocks as Unknown6. Named pools found the other 52,091, by The CryptoLately.com Desk's subtraction.
A plan that asked for trust
Palatinus started with the problem. Miners with graphics cards had made mining "very hard for other people," he wrote1. A new feature in the Bitcoin client, called getwork, let many computers share one job. His plan put it to use.
Members would sign up, enter a wallet address and point their miners at his server1. The server would hand each miner fresh work. When anyone found a block, the reward would be split by work done. That reward was 50 BTC in 2010.
His post gave a worked example. A miner offers 1,000 khash/s, or a million hash attempts each second, for one day. The whole cluster runs at 20,000 khash/s and takes two days to find a block. That miner earns 1.25 BTC1.
He named the catch in the same post. “Disadvantages? You need to trust in central authority (me) that I don't steal block for myself,” Palatinus wrote1. He added a promise: "I don't plan to steal anybody right now".
The first reply came 50 minutes later. That reply argued that two slow machines find blocks at the same rate as one fast machine1. Palatinus granted the point over the long run, then made a second argument.
Both sides, in their own words
Did pooling spread mining out?
“Disadvantages? You need to trust in central authority (me) that I don't steal block for myself”
“These numbers indicate that Bitcoin mining is heavily centralized around a few template-producing pools”
Three blocks on December 16
The pool opened as Bitcoin.cz2. Braiins, the Prague company that runs it now11, says it “mined 3 blocks in its first 24 hours of operation on December 16th”.
Blockchain.com names one of them. “This is the first block known to be pool mined. It was found by Braiins Pool (formerly SlushPool),” its page for block 97,834 says3. The block's timestamp reads 07:16:08 UTC on December 16, 20104. mempool.space, a second block explorer, lists that block's pool as Unknown.
Palatinus ran and funded the pool at first2. Then the pool added a 2 percent fee, Braiins writes. Part of the reason, its history says, was a concern "that zero fees could lead to greater centralization and less competition". Rival pools DeepBit and BTC Guild appeared in the spring of 2011.
Two stories about "first"
Later coverage kept the simple version. ForkLog wrote in 2018 that Slush Pool was "the very first mining pool in existence"11. In the same interview, Braiins co-founder Jan Čapek put a number on it. “During the first four months, we were the only pool in existence and gathered about 30 % of network hash rate,” Čapek said.
Braiins' own history page reads differently. “The concept of pooled mining had been discussed in the community before the launch of Slush Pool, with a few implementations all launching around the same time,” it says2. The 2010 thread holds the same clue. At 14:48 UTC on November 27, a reply pointed to another forum thread with code for cooperative mining1.
Can the data check the 30 percent figure? mempool.space can check little of it. Its weekly file for the pool begins with the week of January 30, 20127. Averaged over 2012's weeks by The CryptoLately.com Desk, its Unknown share comes to 60.1 percent5.
From the pool to Trezor
Palatinus kept building around the pool. On September 10, 2012, he proposed Stratum, a new protocol for pooled mining, Braiins writes2. Stratum became the open standard for pools, by Braiins' account. In 2013, Braiins took a majority stake and took over the pool's operations.
A new company came next. Braiins says he launched Satoshi Labs, "which develops the Trezor hardware wallets"2. The Trezor Model One launched on July 29, 2014, Trezor says12. “We wanted to make a couple of hardware wallets for our friends. But soon we realized that we had found a big market gap,” Palatinus said in Trezor's account.
The pool took the name Slush Pool in 2016 and Braiins Pool in 20222. Braiins bought his remaining stake in 2020.
What the pool data show
mempool.space publishes a weekly share of blocks for each pool it can name5. The CryptoLately.com Desk averaged those weekly shares over each calendar year. In those averages, Braiins Pool, the pool slush started, holds 9.4 percent of weekly blocks in 2012. Its highest such average came in 2018, at 11.0 percent, third among pools that year. Through the week of October 5, 2026, its 2026 average by the same math stands at 1.5 percent.
Average weekly share of Bitcoin blocks, by pool and year, to the week of Oct. 5, 2026, in percent
- Braiins Pool (slush's)
- GHash.IO
- AntPool
- Foundry USA
- Height: Average weekly share, %
Source: mempool.space [5].
Read the chart as a table
| Item | Braiins Pool (slush's) | GHash.IO | AntPool | Foundry USA |
|---|---|---|---|---|
| 2012 | 9.4% | 0.0% | 0.0% | 0.0% |
| 2013 | 9.2% | 8.1% | 0.0% | 0.0% |
| 2014 | 3.4% | 26.4% | 2.2% | 0.0% |
| 2015 | 4.5% | 3.3% | 17.9% | 0.0% |
| 2016 | 5.1% | 0.4% | 21.0% | 0.0% |
| 2017 | 6.2% | 0.0% | 17.6% | 0.0% |
| 2018 | 11.0% | 0.0% | 14.4% | 0.0% |
| 2019 | 7.9% | 0.0% | 12.0% | 0.0% |
| 2020 | 3.8% | 0.0% | 11.0% | 0.1% |
| 2021 | 4.2% | 0.0% | 14.4% | 6.5% |
| 2022 | 5.4% | 0.0% | 16.2% | 22.2% |
| 2023 | 1.7% | 0.0% | 22.7% | 30.5% |
| 2024 | 1.8% | 0.0% | 24.2% | 29.8% |
| 2025 | 1.2% | 0.0% | 18.3% | 29.9% |
| 2026 | 1.5% | 0.0% | 17.9% | 28.3% |
Big pools took a bigger share over time. The year's two largest pools averaged 27.7 percent of weekly blocks in 2017, by The CryptoLately.com Desk's sums5. On the same sums, Foundry USA and AntPool averaged 54.0 percent between them in 2024. Foundry USA tops those yearly averages every year from 2022 on.
In the past year, the same pair led. Foundry USA found 14,779 of 52,381 blocks, and AntPool found 9,4816. Together that comes to 46.3 percent, by The CryptoLately.com Desk's arithmetic. Braiins Pool found 754.
Bitcoin's two largest pools averaged 54.0% of weekly blocks in 2024, up from 27.7% in 2017
Average weekly block share of each year's top three pools, to the week of Oct. 5, 2026, in percent
- Largest pool
- Second-largest pool
- Third-largest pool
- Height: Average weekly share, %
Source: mempool.space [5].
Read the chart as a table
| Item | Largest pool | Second-largest pool | Third-largest pool | Note |
|---|---|---|---|---|
| 2017 | 17.6% | 10.2% | 10.1% | AntPool, BTC.TOP, F2Pool |
| 2018 | 21.6% | 14.4% | 11.0% | BTC.com, AntPool, Braiins Pool |
| 2019 | 17.2% | 13.0% | 12.1% | BTC.com, F2Pool, Poolin |
| 2020 | 17.5% | 14.9% | 12.3% | F2Pool, Poolin, BTC.com |
| 2021 | 15.5% | 14.4% | 12.6% | F2Pool, AntPool, Poolin |
| 2022 | 22.2% | 16.2% | 14.7% | Foundry USA, AntPool, F2Pool |
| 2023 | 30.5% | 22.7% | 13.4% | Foundry USA, AntPool, F2Pool |
| 2024 | 29.8% | 24.2% | 13.2% | Foundry USA, AntPool, ViaBTC |
| 2025 | 29.9% | 18.3% | 12.8% | Foundry USA, AntPool, ViaBTC |
| 2026 | 28.3% | 17.9% | 12.8% | Foundry USA, AntPool, F2Pool |
The GHash.IO scare of June 2014
June 2014 brought an alarm over pool size. Two Cornell researchers raised it. Ittay Eyal, a post-doc, and Emin Gün Sirer, a professor, wrote on June 13 that GHash.IO had reached 51 percent of mining power9. “GHash is in a position to exercise complete control over which transactions appear on the blockchain and which miners reap mining rewards,” they wrote.
Their count covered a 12-hour stretch of 72 blocks9. mempool.space's weekly figures for GHash.IO top out at 39.3 percent, in the weeks starting June 9 and June 16, 20148. On July 16, 2014, GHash.IO pledged to "not exceed more than 39.99% of the overall Bitcoin hashrate," in a statement quoted by TechCrunch's Alex Wilhelm10.
Eyal and Sirer also named the draw. “The people who join the GHash pool do so because GHash has zero fees,” they wrote9. Braiins' history says the pool's 2 percent fee answered a concern that free pools could centralize mining2.
The case for pools
Palatinus made his case on the first day. Small miners who saw steady pay would keep their machines running, he argued1. “I think it is extremely important for bitcoin economy to diversify mining across whole network and not leave mining on few lucky guys with fast GPUs,” he wrote at 16:20 UTC.
Braiins pointed at a second lever in 2018. ForkLog asked whether big pools tied to one company posed a real danger11. “Mining centralization is an important topic. Some of the good questions to ask are: Who owns the hardware? Who has the ability to produce it and pick to whom to sell it?” Čapek answered. He named Bitmain as the dominant hardware maker. Bitmain owns AntPool, b10c notes13.
The case against
b10c, a Bitcoin developer, measured the outcome in April 202513. The post counted blocks by the tags and addresses pools leave in them. “These numbers indicate that Bitcoin mining is heavily centralized around a few template-producing pools,” b10c wrote. A block template is the list of transactions a pool hands its miners to work on.
A second layer sits under those tags. Several smaller pools appear to relay AntPool's templates under their own names, the post says13. Its list of pools "assumed to be part of the AntPool & friends group" includes Braiins. That entry links to evidence on template similarities and invalid jobs. By b10c's count, six pools mined more than 95 percent of blocks.
What to watch
Each side needs a different result. Palatinus's 2010 case needs smaller pools to win back share. b10c points to pools such as Ocean and DEMAND, "where miners build their own template"13. mempool.space's weekly files will show whether Foundry USA holds near 28.3 percent, its 2026 average by The CryptoLately.com Desk's math5. The same files will show whether Braiins Pool climbs from its 2026 average of 1.5 percent.
Sources
- slush, "Cooperative mining" (thread now titled "[4+ EH] Slush Pool (slushpool.com); Overt AsicBoost; World First Mining Pool"), Bitcointalk, Nov. 27, 2010, https://bitcointalk.org/index.php?topic=1976.0
- Braiins, "Our Mining Pool Story: Bitcoin mining since 2010," Internet Archive capture of Oct. 4, 2022, https://web.archive.org/web/20221004042528/https://braiins.com/pool/story
- Blockchain.com, "Bitcoin Block 97,834," read Oct. 13, 2026, https://www.blockchain.com/explorer/blocks/btc/97834
- mempool.space, "Block 97,834" (block API), read Oct. 13, 2026, https://mempool.space/api/v1/block/000000000000dcaab612dcfd2a7b281c794a6da9006773dab55141ac608bfc86
- mempool.space, "Mining pools, all time" (pools/all), with each pool's weekly share file (pool//hashrate), read Oct. 13, 2026, https://mempool.space/api/v1/mining/pools/all
- mempool.space, "Mining pools, past year" (pools/1y), read 05:39 UTC on Oct. 13, 2026, https://mempool.space/api/v1/mining/pools/1y
- mempool.space, "Braiins Pool weekly share" (pool/braiinspool/hashrate), read Oct. 13, 2026, https://mempool.space/api/v1/mining/pool/braiinspool/hashrate
- mempool.space, "GHash.IO weekly share" (pool/ghashio/hashrate), read Oct. 13, 2026, https://mempool.space/api/v1/mining/pool/ghashio/hashrate
- Ittay Eyal and Emin Gün Sirer, "It's Time For a Hard Bitcoin Fork," Hacking, Distributed, June 13, 2014 (Internet Archive copy), https://web.archive.org/web/20140616163248/http://hackingdistributed.com:80/2014/06/13/time-for-a-hard-bitcoin-fork/
- Alex Wilhelm, "Popular Bitcoin Mining Pool Promises To Restrict Its Compute Power To Prevent Feared '51%' Fiasco," TechCrunch, July 16, 2014, https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/
- ForkLog, "ForkLog Exclusive: Slush Pool Breaks Down Bitcoin Mining Ins and Outs, Market Slump Consequences for Miners," Nov. 26, 2018, https://forklog.com/en/forklog-exclusive-slush-pool/
- Billy Campbell, "A decade of pioneering: 10 years since Trezor's first hardware wallet revolution," Trezor, July 29, 2024, https://trezor.io/blog/news/a-decade-of-pioneering-10-years-since-trezors-first-hardware-wallet-revolution
- b10c, "Bitcoin Mining Centralization in 2025," b10c.me, April 15, 2025, https://b10c.me/blog/015-bitcoin-mining-centralization/