More Rocket Fuel: Announcing Our Series B with Lakestar and GV

Dark blue rocket taking off with Blockchain's logo stacked.When Blockchain started out as an open source project, we set out to build tools that would make it easy for anyone to use digital currencies. We still pursue this goal everyday.

I’m extremely proud and humbled by the progress we’ve made – millions of active users around the world, exchange partnerships in 34 countries, billions in monthly consumer volume, and an API platform used by some of the biggest companies in our field.

Today, I’m excited to announce that we’ve raised a Series B of $40 million with Lakestar and GV (formerly Google Ventures) with additional participation from Nokota Management and Digital Currency Group. Our existing investors – Lightspeed Venture Partners, Mosaic Ventures, Prudence Holdings, Virgin, and Sir Richard Branson (Virgin Group) – also participated in the round. Their continued support is an honor.

Our Series B represents the most substantial investment in the fintech space since Brexit and is the largest Series B raised by any digital currency company to date. This brings our total capital raised to over $70 million and we’re thrilled to welcome some of the most well-respected investors in the world to the Blockchain family.

Our mission “to create an open, accessible, and fair financial future for billions across the globe, one piece of software at a time” is a lofty one. This capital moves us one step closer to delivering on that mission and will ensure we can take a very long-term view.

As the market leader, you can expect us to make big, bold bets in research and development as well as further our expansion efforts globally. You can also expect new products aimed at allowing anyone to transact, save, or hedge digital assets with greater speed, efficiency and control.

Innovating, disrupting, revolutionizing a century old industry takes time. We’ve made significant strides, but we’re just getting started. Thank you for joining us on the very first part of our journey to the moon – rest assured we have the rocket fuel to get there!

Peter & the Blockchain Team

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More Rocket Fuel: Announcing Our Series B with Lakestar and GV

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Bitcoin Core Version 0.14.2 Released

Bitcoin Core Version 0.14.2

Bitcoin Core version 0.14.2 is now available.

This is a new minor version release, including various bugfixes and
performance improvements, as well as updated translations.

Please report bugs using the issue tracker on GitHub.

Subscribe here to receive
security and update notifications.


Bitcoin Core is extensively tested on multiple operating systems using
the Linux kernel, macOS 10.8+, and Windows Vista and later.

Microsoft ended support for Windows XP on April 8th,
No attempt is made to prevent installing or running the software on Windows XP,
you can still do so at your own risk but be aware that there are known
instabilities and issues. Please do not report issues about Windows XP to the
issue tracker.

Bitcoin Core should also work on most other Unix-like systems but is not
frequently tested on them.

Notable changes

miniupnp CVE-2017-8798

Bundled miniupnpc was updated to 2.0.20170509. This fixes an integer signedness error
(present in MiniUPnPc v1.4.20101221 through v2.0) that allows remote attackers
(within the LAN) to cause a denial of service or possibly have unspecified
other impact.

This only affects users that have explicitly enabled UPnP through the GUI
setting or through the -upnp option, as since the last UPnP vulnerability
(in Bitcoin Core 0.10.3) it has been disabled by default.

If you use this option, it is recommended to upgrade to this version as soon as

Known Bugs

Since 0.14.0 the approximate transaction fee shown in Bitcoin-Qt when using coin
control and smart fee estimation does not reflect any change in target from the
smart fee slider. It will only present an approximate fee calculated using the
default target. The fee calculated using the correct target is still applied to
the transaction and shown in the final send confirmation dialog.

0.14.2 Change log

Detailed release notes follow. This overview includes changes that affect
behavior, not code moves, refactors and string updates. For convenience in locating
the code changes and accompanying discussion, both the pull request and
git merge commit are mentioned.

RPC and other APIs

  • #10410 321419b Fix importwallet edge case rescan bug (ryanofsky)

P2P protocol and network code

  • #10424 37a8fc5 Populate services in GetLocalAddress (morcos)
  • #10441 9e3ad50 Only enforce expected services for half of outgoing connections (theuni)

Build system

  • #10414 ffb0c4b miniupnpc 2.0.20170509 (fanquake)
  • #10228 ae479bc Regenerate bitcoin-config.h as necessary (theuni)


  • #10245 44a17f2 Minor fix in build documentation for FreeBSD 11 (shigeya)
  • #10215 0aee4a1 Check interruptNet during dnsseed lookups (TheBlueMatt)


  • #10231 1e936d7 Reduce a significant cs_main lock freeze (jonasschnelli)


  • #10294 1847642 Unset change position when there is no change (instagibbs)


Thanks to everyone who directly contributed to this release:

  • Alex Morcos
  • Cory Fields
  • fanquake
  • Gregory Sanders
  • Jonas Schnelli
  • Matt Corallo
  • Russell Yanofsky
  • Shigeya Suzuki
  • Wladimir J. van der Laan

As well as everyone that helped translating on

Source: blog
Bitcoin Core Version 0.14.2 Released

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Improving Our Fee Recommendations

At Blockchain, we strive to make digital currency safe and easy for everyone to use. Part of that goal is providing effective miners’ fee recommendations for every transaction our users make. Bitcoin has recently reached its peak capacity, with a consistent queue of tens of megabytes of transactions waiting to be confirmed. As bitcoin interest and activity continues to grow (and we can expect this trend to continue), we’ve made two important changes to our wallet:

  • The introduction of a new fee recommendation algorithm aimed at being more reactive to changing network conditions and providing a better, more consistent experience for our users.
  • A new ‘Priority’ option which aims to have your transaction included in a block within 60 minutes. This feature is currently available via our Web and Android wallets and will be included in our upcoming iOS release; available the week of June 19th.

How Fee Recommendations Work

In Bitcoin, transaction fees are used to incentivize miners to confirm transactions by including them in a block which is then appended to the previous blocks, creating a ‘block chain’. Rational miners will select transactions paying a higher fee per byte. ‘Fee per byte’ is represented in satoshis/B (‘sat/B’ for short) and can be seen when viewing a transaction on our explorer:

The breakdown of a bitcoin transaction, with how much of a fee per byte highlighted and displayed as satoshis per byte.

Recommending a fee that will achieve a confirmation within a specific time window would require knowing what fee per byte future transactions will pay and therefore is not possible to do reliably. There are many approaches to fee recommendations. Bitcoind, for example, tracks how long past transactions took to confirm and how much they paid in order to determine a fee level which will confirm a transaction in a given number of blocks most of the time. This gives conservative estimates but does not react quickly to changing network conditions (which can be very dynamic) and often results in users either paying too much or too little.

Our Approach

In looking at trends of mempool size growth, it’s apparent the mempool can experience rapid and unpredictable increases in size. Therefore it is important that our fee recommendations adjust rapidly as transactions using slow-to-update fee recommendation algorithms that are not overly conservative (expensive) can experience dramatic increases in confirmation time.

Our approach observes recent network activity to determine the rate of growth for each fee level. This gives us a picture of how much the network is paying for blockspace and in what proportions. Using that data and a snapshot of bytes in the mempool at every fee level, we extrapolate mempool state into the near future to find a fee level that puts a transaction at the right place in the unconfirmed queue for a targeted confirmation range. This produces fee recommendations that adapt more quickly to abrupt changes in network conditions and results in a more consistent user experience.

We plan on continuing to improve our fee recommendations in the future.

Visualizing Mempool Activity

Our algorithm requires that we capture mempool state data over time in order to determine fee level growth in bytes per second. As a result, we’re able to produce visualizations depicting mempool activity over time:

A visualization of fee recommendations per byte based on mempool activity

In addition to plotting bytes per fee level, we also include in the chart our ‘regular’ and ‘priority’ fee level recommendations for any given moment in time (seen as vertical lines in red and blue). This new chart is available here.

We hope this tool provides people with a better understanding of how the mempool and fees work. Our current fee recommendations are also available via our API.

Priority Fee Option

As pictured below, the new Priority fee option can be found in our web and Android wallets today. If you’re on iOS, stay tuned for our upcoming release which will include this priority fee update. 

The Blockchain wallet send screen demonstrating the new fee options, regular and priority.

Feeling intrigued? Visit our careers page to view our open positions and help us build an open, accessible and fair financial future. 

The post Improving Our Fee Recommendations appeared first on Blockchain Blog.

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Recover your wallet, quick and easy

Just follow our 10-step guide

  1. Visit Click “Begin Recovery.”

2. Input your backup data in the appropriate boxes. Your backup data can be found on your backup PDF, which you should have saved when you created your wallet. Alternatively, you can click “Import from Backup” in the upper-right corner, and upload the PDF itself.

Note: Importing your backup PDF is the more convenient option, as it will allow you to skip the manual input of your data. Using this method, you also will not need to scan your QR code.

3. If you have forgotten your password, click “Forgotten password?” beneath the Wallet Password box. Input your account email and your wallet identifier, which is on the first page of your PDF backup. Click “Request Decryption Key.” The key will be sent to your email address. Input this key into the Wallet Password box of the Recovery Tool.

4. Scan the QR code on your backup PDF.

4. Click “Next.”

5. You will be taken to the Configure Recovery Settings page. If you have had your wallet for a relatively long time (or have used it frequently), increase the batch size so the scan will include more potentially balance-holding addresses. Click “Next.”

6. You will be taken to the Discover Wallet Funds page. Here, you will be able to scan to recover funds from addresses in your wallet. Click “Begin Discovery” and wait for the scan to complete.

7. The scan will alert you to funds found. Click “Next.”

8. If funds are found, click “Begin Recovery.”

9. When your bitcoin has been recovered, you will to choose to send your funds via Blocktrail or Insight. Clicking either option will push your bitcoin to the network. The bitcoin will then be transferred to your specified wallet address.

10. Congratulations! You have recovered your wallet! If you have any questions, please do not hesitate to contact us at [email protected]

Recover your wallet, quick and easy was originally published in The BTC Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

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Celebrate bitcoin’s milestones on these holidays

Bitcoin has already begun to radically change how people transact. Wondering how we got to where we are today? Here are a list of bitcoin’s milestones to date that have helped define the ecosystem and build a new financial future for millions across the globe.

Multiple balloons tied to a suitcase. Each balloon has a symbol representing one of the bitcoin holidays covered in the post.

Bitcoin’s White Paper – October 31, 2008

Bitcoin’s initial round of exposure to the world was an academic paper called “Bitcoin: A Peer-to-Peer Electronic Payment System”. Written by an unknown person or persons using the alias Satoshi Nakamoto, the paper laid the groundwork for the digital currency and the peer-to-peer decentralized payment network that powers it all. It’s been speculated that Halloween was intentionally chosen as a release date.

The Genesis Block – January 3, 2009

A few months after the release of the White Paper, Satoshi mined the very first bitcoin block, which was the first evidence of activity recorded on the block chain. This activity, referred to as the Genesis Block or Block 0, is commonly celebrated as the other half of bitcoin’s birthdate; the White Paper being the initial half. Both being important milestones, Block 0 represents the genesis of bitcoin in action. The first official bitcoin transaction followed soon after, with cryptographer Hal Finney receiving a total of 10 BTC from Nakamoto on January 12, 2009.

Bitcoinween – October 31, 2014

During 2014’s spooky season, a contest dubbed “Bitcoinween” was organized by our very own Nicolas Cary. The pumpkin carving contest put the spotlight on bitcoin-accepting nonprofits, with Cary donating $500 in bitcoin to the contest winner’s nonprofit of choice. While Bitcoinween was only a one-year event, one thing is clear: bitcoin is an epic transaction medium for nonprofits.

Bitcoin Pizza Day – May 22, 2010


This holiday generates quite a bit of buzz on social media each year. Despite what a quick Google Search might lead newer users to think, this bitcoin milestone didn’t kick off because we’ve got some strange pizza fetish. The truth is that pizza was the first documented purchase of a good with bitcoin.

In May of 2010 user Laszlo posted an offer to pay 10,000 BTC to anyone who would order him two pizzas. At the time, bitcoin was still in its infancy and hadn’t been used for purchasing much of anything. On May 22, Laszlo’s offer was accepted and his bitcoin-for-pizza transaction marked the very beginning of bitcoin’s use potential as an everyday currency. The 10,000 BTC transaction was only worth $41 USD at the time, but now it holds a value of over 20 million dollars.

Fast forward to today, there are plenty of ways to buy yourself a slice of cheesy goodness, like Pizza For Coins, or through gift card e-tailers eGifter or Gyft. Thank you, Laszlo!

The Halving – once every four years

Illustration of a rocket awaiting launch with a countdown and stats on bitcoin's 2016 halving.

Halving is a part of the bitcoin mining process. In short, bitcoin miners are rewarded with bitcoin for each block of transactions they validate. How much they receive is divided in half during the halving, which occurs about once every four years (or once every 210,000 blocks). To date, there have been two halvings. The first was in November 2012, which reduced the reward from 50 to 25 BTC. Last year, gatherings around the globe celebrated the second halving event, which saw it reduced again to 12.5 BTC.

The reward halving makes bitcoin increasingly difficult to mine. As its demand and utility also rises, this creates scarcity, which can have a significant influence on bitcoin’s market value.

And there you have it, a quick and (hopefully) insightful primer on  bitcoin’s milestones that have inspired parties, fundraising efforts, and a worldwide pizza party that’s been happening on the same date for the past 7 years.

The post Celebrate bitcoin’s milestones on these holidays appeared first on Blockchain Blog.

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Buy bitcoin with your wallet! has partnered with US-based global digital asset exchange Kraken, leveraging its Kraken Direct service and allowing users to quickly and easily purchase bitcoin directly from the wallet.

Kraken Direct currently supports 49 US states, funding bitcoin purchases through ACH bank transfer. plans to expand bitcoin purchasing capabilities beyond the United States in the coming weeks.

How to buy bitcoin at

Note: The following steps apply to both the web and mobile wallet.

  1. Click or tap “Buy Bitcoins” on the menu sidebar.

2. Select your region (at this time, only users in the USA are able to buy bitcoin).

3. Select a purchase method (at this time, only Glidera is supported).

4. Create an account with or log in to Glidera.

5. Approve’s API request, enabling access to your Glidera account.

6. Enter your wallet password.

7. Enter the amount (in BTC or USD) that you wish to purchase.

8. Congratulations! You’ve purchased bitcoin. Funds will appear in your wallet as soon as your payment to Glidera has been cleared. (ACH transfers can take up to four business days.)

You can view your pending order on the main page in your wallet.

Contributing editor: Adam Kohut.

Buy bitcoin with your wallet! was originally published in The BTC Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

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Buying bitcoin is now available for Blockchain wallets on iOS

Late last year, we announced a partnership with Coinify that allowed our users in Europe to, for the first time ever, seamlessly and expediently buy bitcoin from within their Blockchain wallets without compromising user security or control. This partnership was aimed at making our wallet infinitely more user friendly and, ultimately, more accessible for the mass market. Today we take the next step in delivering greater accessibility.

Our team is excited to announce that iOS users in Europe are now able to buy bitcoin from within their Blockchain wallets using the same seamless and user friendly Blockchain-Coinify integration available to web users.

Like you may have already discovered on web, your Blockchain wallet can be funded in a flash with credit and debit cards, or directly from your bank account, which is subject to bank transfer speed. Each of these methods have made their way to iOS to make sure users can acquire digital currency easily, however they choose.

This important update brings us one step closer to building an open, accessible and fair financial future for the growing number of mobile users. We look forward to rolling out this integration to our Android wallet users in the near future.

The post Buying bitcoin is now available for Blockchain wallets on iOS appeared first on Blockchain Blog.

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The faces of

It’s true — we are human through and through! Read on for short Q&As with a few members of our Chinese team.

From left, China team members Chris Zhu, Kevin Pan, and Tian Zhao.

Name and job title

Kevin Pan, director.

How long have you been with

Two years and one month.

Your #1 tip to new bitcoiners?

Buy bitcoins and take good care of them. Don’t sell them for five years. Don’t lose hope. Spend the time to watch and learn about the bitcoin industry. Don’t try to be a trader without industry knowledge. For most people, a good idea is to buy coins and forget them (securely).

Where do you see the bitcoin industry in 10 years?

Full of hope—maybe 50 times bigger than it currently is. It’s a great experiment.

How can bitcoiners most effectively protect themselves?

Don’t lose control of your own coins. Do use 1password or Lastpass.

What is your favorite meal?

Seafood and hot pot.

Name and job title

Chris Zhu, senior product manager.

How long have you been with

Nearly two years.

Your #1 tip to new bitcoiners?

Bitcoin is real money—hold on to it.

Where do you see the bitcoin industry in 10 years?

In 10 years, bitcoin will rise to US$100,000.

How can bitcoiners most effectively protect themselves?

Run the same wallet (the same private-key or backup) on a different device. Run that wallet on iOS or Mac. I think Windows and Android aren’t as safe, because they’re very easy to root.

What is your favorite meal?

A hamburger with vegetable salad.

Name and job title

Tian Zhao, senior developer.

How long have you been with

Two years.

Your #1 tip to new bitcoiners?

Keep your bitcoin in the wallet to make sure it is safe and secure!

Where do you see the bitcoin industry in 10 years?

I think bitcoin will be a very powerful and effective channel which can be used daily. It will be a complementary source of commerce to existing payment methods.

How can bitcoiners most effectively protect themselves?

Do your research. Don’t blindly follow or rely on news, which can be fake. This way, you can avoid scams and scam ICOs (initial coin offerings).

What is your favorite meal?

Hot pot!

The faces of was originally published in The BTC Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

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