Support for BIP109

BIP109 is a proposal to increase the block size to 2MB endorsed and implemented in Bitcoin XT and Bitcoin Classic. For list of supporters of BIP109, see the Bitcoin Classic website.

Companies that supported BIP101

BIP101 is a proposal to increasing block size and was implemented in Bitcoin XT. It did not gain enough traction as has now been withdrawn. The following companies voiced their public support of BIP101 in 2015:

November 3rd

Coinbase is a bitcoin wallet and exchange company headquartered in San Francisco, California. It operates exchanges between bitcoin and fiat currencies in 26 countries, and bitcoin transactions and storage in 190 countries worldwide. More than 2 million users make advantage of their bitcoin wallet service.
(Proof)

September 15th

Coinify drives mainstream adoption of blockchain payments for merchants and consumers. 10,000 merchants benefit from Coinify's Payment Service enabling free, instant settlements in a fraud-free and chargeback-free payment environment, while consumers get access to secure one-click payments. Coinify is backed by a multi-million capital injection from SEED Capital (funded by the Danish Government) and Accelerace, and is the leading European blockchain payments provider.

August 24th

BitPay is a global bitcoin payment service provider headquartered in Atlanta, Georgia. It was founded in May 2011 by Tony Gallippi and Stephen Pair. BitPay provides payment processing services for merchants, and is one of the largest Bitcoin payment processors. In 2014, BitPay started processing $1 million USD daily.

Bitnet provides a digital commerce platform enabling enterprise-scale merchants to accept bitcoin payments. Bitnet's engineering, product, and business development team helped build and manage the world's largest payment gateway, CyberSource, which was sold to the world's largest payment network, Visa, for $2 billion in 2010.

Circle is a digital currency company headquartered in Boston, Massachusetts. Founded by serial Internet entrepreneur Jeremy Allaire, Circle aims to build on the open foundations of Bitcoin to deliver products that can facilitate mainstream adoption of digital currency. Circle has received $76 million in venture capital investments.

Blockchain is currently the provider of the world's most popular Bitcoin wallet, the most widely used Bitcoin APIs, the most popular block explorer and search engine, and has what is widely recognized as the strongest, most trusted brand in Bitcoin. Experiencing a rapid expansion during the course of two years, Blockchain exploded from 100,000 users to over 3,500,000 users.

Xapo combines the convenience of an everyday bitcoin wallet with the security of a deep cold storage vault. The company has raised $40 million from Benchmark, Greylock Partners, Index Ventures, Fortress Investment Group, Ribbit Capital and Emergence Capital Partners.

itBit is a global bitcoin exchange offering institutional and retail investors a powerful platform to buy and sell bitcoin. The company received more than $5 million in venture capital from Canaan Partners, RRE Ventures, Liberty City Ventures, and angel investors Jay W. Jordan II and Ben Davenport.

BitGo launched the first ever multi-signature Bitcoin wallet in 2013, and continues to create innovative security services on top of emerging industry standards. The company operates a security-as-a-service platform that powers the industry's most secure, enterprise Bitcoin wallet with solutions for corporate treasury and key management. The company has raised $12 million in funding led by Redpoint Ventures.

KnCMiner delivers efficient, secure and green blockchain power to the world. The company is an expert in ASIC design as well as in building, equipping and running large data centers on renewable green hydropower. It raised the total of $29 million in venture capital investments.

Signed Letter (pdf)