Martin Fowler
Software design writer and chief scientist at Thoughtworks; wrote Refactoring and Patterns of Enterprise Application Architecture.
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What they believe
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The usual trade-off between quality and cost does not apply to software: high internal quality is the cheaper way to produce it.
With this article I'll explain that this trade-off does not apply to software - that high quality software is actually cheaper to produce.
martinfowler.comSaid 29 May 2019This on korrents
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Successful microservice systems almost always began as a monolith that grew too big, and systems built as microservices from scratch end up in serious trouble.
Almost all the successful microservice stories have started with a monolith that got too big and was broken up
martinfowler.comSaid 3 Jun 2015This on korrents
The bold line is korrents’ wording; the quote is theirs. These 2: what they wrote before what they said aloud, one per source, newest first.
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Beliefs
Korrents What they believe 21 beliefs — each backed by an exact quote.
Each is a — compiled by korrents.com, not by them: the one-line wordings are korrents', the quotes are theirs.
Recent
Nothing in a fifty-year career has hit the industry with the magnitude of AI; it is a whole size difference from anything before it.
Well, nothing has hit with the magnitude of AI. That's I mean, this is a a whole size difference from anything that we've faced before.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
Every earlier wave, the internet included, had to be argued for; AI is the first where nobody has to be persuaded that it matters.
but the thing about AI is that, you know, all of many of these things we were talking about how important they were and how valuable were and trying to persuade people of the importance of them. Yes, even the internet. That may sound surprising, but there were people who would weren't thinking that was important. Um but AI, there's kind of no argument about how important it is. People can't can I mean, you cannot put blinkers on to deny the importance of this thing.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
Skepticism about a new technology only works if it is total enough to be turned on itself, which is what forces you to stay curious.
My skepticism has to be absolute and total, which means I have to be skeptical about my skepticism. And that requires that curiosity.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
Show 18 more
Using an AI tool well is something you have to learn, exactly as it was with object orientation; a bad first impression proves nothing.
one of the things that I took from that was to use this tool well, you have to learn how to use it well, which was also something very true of object orientation.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
AI will repeat Agile's pattern: sound core ideas surrounded by a huge snake oil industry that is hard to tell apart from the real thing.
Um I think another similarity is I mean, the core notions uh behind Agile and extreme programming are solid and good, but a huge snake oil industry appeared around it, the Agile industrial complex as I like to refer to it. Um and that will happen. That is happening with AI right now, and it's often hard to see the difference between where is the snake oil and where is the real stuff.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
Predictions that nobody will write code soon dodge the question of what code is: prompting a model is still producing something we will have to read and change.
I go to myself, "Well, yeah, but what do you mean by code?" Because that kind of implies nobody's writing anything. Well, we're at least doing some prompting. We're having some interaction with the genie. What's that going to be if it's not some form of code in some way? I think the nature of what code is is going to be quite possibly for a very radically different. But I think there is still a need to produce it and be able to interact with it in some way.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
Large-scale confusion and panic is the order of the day at companies adopting AI, right across the board.
Um at the moment large-scale confusion and panic is pretty much the order of the day right across the board.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
There will be some really bad security incidents this year, because people rushing to hand agents control of things like their email are not paying attention.
I am very much concerned we're going to have some really bad security incidents um over this year because people are just not paying attention.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
One person with many agents is probably not the right answer; the better bet is two-pizza teams made more effective, with pairs of humans steering the agents together.
My bet is on the more effective two pizza teams. Um and it it's also some interesting, you know, feedback we're beginning to get in terms of pair programming. I mean, with pair programming, do you say pair programming is the human and the genie? Or is it two humans and and genies? Because if it's two of us, we can control the genies perhaps a little bit better.
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
The Venn diagram of developer experience and agent experience is a circle: well-modularised code and good tests help the agents exactly as they help the humans.
which is that the the Venn diagram of developer experience and agent experience is a circle. And the point here is that, you know, what we do that that's good for the agents is good for the humans and vice versa. I'm hearing a lot of feedback saying, "Yeah, actually, if you have well-modularized code, that actually makes it easy for the agents to work with."
Martin Fowler & Kent Beck: Frameworks for reinventing software, again and again Said 7 Apr 2026
The usual trade-off between quality and cost does not apply to software: high internal quality is the cheaper way to produce it.
With this article I'll explain that this trade-off does not apply to software - that high quality software is actually cheaper to produce.
Is High Quality Software Worth the Cost? Said 29 May 2019
Poor internal quality begins to slow a team down within a few weeks, so almost no project is short enough for cutting corners to pay off.
Developers find poor quality code significantly slows them down within a few weeks.
Is High Quality Software Worth the Cost? Said 29 May 2019
Cruft is not carelessness: even the best teams inevitably create it, because the right design is only visible once the software has been built.
even the finest teams will inevitably create some cruft as they work
Is High Quality Software Worth the Cost? Said 29 May 2019
Successful microservice systems almost always began as a monolith that grew too big, and systems built as microservices from scratch end up in serious trouble.
Almost all the successful microservice stories have started with a monolith that got too big and was broken up
MonolithFirst Said 3 Jun 2015
Build a new application as a monolith first, even when you are confident it will eventually need microservices.
This leads to a powerful argument for a monolith-first strategy, where you should build a new application as a monolith initially, even if you think it's likely that it will benefit from a microservices architecture later on.
MonolithFirst Said 3 Jun 2015
Service boundaries cannot be got right at the start, and moving functionality between services is far harder than moving it inside a monolith.
But even experienced architects working in familiar domains have great difficulty getting boundaries right at the beginning.
MonolithFirst Said 3 Jun 2015
Test coverage is a tool for finding untested code and says nothing about how good the tests are.
Test coverage is of little use as a numeric statement of how good your tests are.
TestCoverage Said 17 Apr 2012
Making test coverage a target destroys it, because high coverage numbers are easy to reach with worthless tests.
If you make a certain level of coverage a target, people will try to attain it. The trouble is that high coverage numbers are too easy to reach with low quality testing.
TestCoverage Said 17 Apr 2012
Total test coverage is a warning sign rather than an achievement: it smells of tests written for the number.
I would be suspicious of anything like 100% - it would smell of someone writing tests to make the coverage numbers happy, but not thinking about what they are doing.
TestCoverage Said 17 Apr 2012
Software productivity cannot be measured, because there is no way to measure a development team's output.
the reason we can't measure productivity is because we can't measure output
CannotMeasureProductivity Said 29 Aug 2003
Lines of code cannot measure productivity, because better-designed code is shorter.
Any good developer knows that they can code the same stuff with huge variations in lines of code, furthermore code that's well designed and factored will be shorter because it eliminates the duplication.
CannotMeasureProductivity Said 29 Aug 2003
What is a korrent?
A korrent is a belief a person has stated in their own words: one sentence stating the claim, backed by a quote and a source, kept at korrents.com.
Under a name here, the quoted block is what they actually said. The korrent beneath it is the claim those words support, in korrents' wording — tap it to see the record, its source, and who else holds it.
Nobody here wrote their own korrents. They are compiled from public statements, and a person can change their mind, which is recorded too.
Recommends rcmnd
rcmnd What they recommend 4 things — each backed by an exact quote.
Compiled by rcmnd.app, not by them: the quotes are theirs, and each links to the post it was copied from.
Recent
Loved The Mythical Man-Month
This point of view has been a strong influence upon my career, the pursuit of conceptual integrity underpins much of my work. The anniversary edition of this book is the one to get, because it also includes his even-more influential 1986 essay “No Silver Bullet”.
martinfowler.com 5 May 2026
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Loved Patterns of Distributed Systems
As the pattern collection took shape, he contacted Pearson to turn this into a book, which I am proud to add to my signature series. The final book contains thirty patterns, each illustrated with explanatory text, many with sequence diagrams to explain the complex interactions, and all with code samples that clarify the all-important details.
martinfowler.com 1 Jan 2023
Loved Continuous Delivery: Reliable Software Releases through Build, Test, and Deployment Automation
It seems to me that a book that can show you how to deliver your software frequently and without the usual stresses is a no-brainer to read. For your team's sake, I hope you agree.
martinfowler.com 1 Jan 2010
Show 1 more
Loved xUnit Test Patterns: Refactoring Test Code
I've been excited by this project since I first heard about it. (I had to launch a commando raid to steal this book from Bob Martin because I wanted it to grace my series instead.)
martinfowler.com 1 Jan 2007
What others say about xUnit Test Patterns: Refactoring Test Code →
Where they publish
Site martinfowler.com His site: articles, book chapters and bliki entries on software design. Has a feed.
Recent
- Bliki: LLM Voice 29 Oct 2026 Sometimes when I read a post, I get the growing feeling that I'm reading the output of an LLM. I can't necessarily define why, although there are the common tells (it's not the em-dashes, it's the load-bearing tapestrie…
- Fragments: October 28 28 Oct 2026 Andrej Karpathy sees a widening gap in how people see LLM capabilities. The general public has mostly not interacted with these systems. When they have, it looks like a derpy chatbot. The majority of professionals still…
- Fragments: October 21 21 Oct 2026 Gergely Orosz is frustrated at those that entered his explicitly “No AI” essay competition and used AI. He goes on to say: When I start to suspect some part is AI about someone I don’t know: how can I tell how much of i…
Show 17 more
- When Software Meets Hardware 15 Oct 2026 , engineering principles remain largely the same, but the sensible defaults often change. Kuldeep Singh describes our experience modernizing a large IoT fleet of battery-powered sensors. Our familiar principles remained…
- Build your slide template 14 Oct 2026 Building a slide template starts with three foundational choices — colours, fonts and layouts. Sumeet Gayathri Moghe covers the basics of color theory and how to build a reusable palette, the essentials of typography, i…
- The Craft of Practitioner Voice 13 Oct 2026 A couple of months ago Jim Highsmith explained how practitioners writing for each other forms a distinct style of writing. He now adds a section to the article with more detail on the craft of how we write in this style…
- Are Harnesses Worth the Cost? 13 Oct 2026 Naresh Jain compares coding agents building the same API service with and without a behavioral harness. A frontier model, GPT-6 Sol, passed every external evaluation either way. But a cost-optimized model, GPT-6 Luna, s…
- Fragments: October 4 5 Oct 2026 In response to my last fragments (probably the bit about us worrying if LLMs have consciousness when we when we should be wondering why they don’t have a conscience) “Metalanguage” replied: we shipped the id and forgot…
- Principles for effective slides 30 Sept 2026 Not every presentation needs slides, but when they earn their place, they work as a visual channel that complements the speaker rather than replacing them. Sumeet Gayathri Moghe sets out the principles that follow from…
- Bliki: Sensible Default 29 Sept 2026 A Sensible Default is a practice that, absent some overriding context, should be used when carrying out a certain kind of task. In software development such sensible defaults might include things like “use version contr…
- Fragments: September 29 29 Sept 2026 Simon Willison: The more time I spend working with coding agents, the more convinced I am that they make software engineering even harder We can do amazing things with them, but unlocking their full potential requires e…
- Fragments: September 24 24 Sept 2026 Rob Bowley is “flipping tables in his head” with anger at the current media coverage of the danger of AI killing us all The risk I’m worried about isn’t a future machine deciding to wipe us out. It’s today’s AI, being w…
- Healthy Feedback 24 Sept 2026 Human collaboration, like most things, improves with feedback. But it's not obvious how to make feedback effective. Anuja Karnik and Sumeet Gayathri Moghe pass on a bevy of tips for healthy feedback, based on the princi…
- I don't like LLMs 17 Sept 2026 I have a lot of mixed feelings about AI and LLM technology. I’m fascinated by its effect on our profession, excited by the potential gains in productivity - and thus the products we could rapidly build. On the other han…
- Fragments: September 16 16 Sept 2026 Reports of agentic hacking continue, in this case it happened back in May and it seems OpenAI did not disclose that they were responsible. Simon Willison sees two options: After the Hugging Face and Wiki attacks OpenAI…
- Nail the Narrative 15 Sept 2026 Sumeet Gayathri Moghe finds many folks building presentations get tangled in building slides without a coherent narrative. He advises distilling the big idea, visualizing the audience, and building a structured storylin…
- Social Media Engagement: summer 2026 9 Sept 2026 A quick survey of recent engagement of my posts on social media, indicating which service has by far the most engagement, and which service has seen a precipitous decline since early 2025. more
- Fragments: September 8 8 Sept 2026 Christian Catalini says we’re in a situation where we are vastly reducing the cost of generating things, but not the cost of verifying them:. This explains why the first major AI products appeared in chat, image generat…
- Do you even need a presentation? 8 Sept 2026 Like me, Sumeet Gayathri Moghe is tired of poor presentations with bad slide decks. He's started to write a series of posts on how to avoid these calamities, beginning with a post that questions whether a presentation i…
- Bliki: Paracelsus Maxim 2 Sept 2026 The difference between a medicine and a poison is dosage. Often we talk about certain habits, in programming or life, are good or bad. But few things are simple binaries. Some vary with context: reading a book is a good…
Link verified 20 Sept 2026. Recent items update automatically from the channel.
x.com @martinfowler Their X account.
Recent
- Bliki: One of the curses of the growth of AI is the amount of LLM-Voice I read on the web 29 Oct 2026 martinfowler.com
- Rachel's Ramblings: Why are good developers so wary of agentic development? 29 Oct 2026 martinfowler.com
- Fragments: widening perception gap of LLMs, notes from Foocamp, today is 1997, a shift to supervisory control, Eric Evans keynote, Thoughtworks's token sourcing strategy 28 Oct 2026 martinfowler.com
Show 17 more
- Fragments:LLM generated prose generates rejection, cancellation of Grade Hopper celebration, using AI to assist debugging unfamiliar code 21 Oct 2026 martinfowler.com
- When @thinkuldeep took on modernizing a huge fleet of IoT sensors, he found that while his engineering principles remained largely the same, he formed a new set of Sensible Defaults for the new environment. 15 Oct 2026 martinfowler.com
- Slide design is based on choices of colors, fonts, and layouts. Sumeet demonstrates how to think about these, and why the best layout is usually a blank one. 14 Oct 2026 martinfowler.com
- A couple of months ago Jim Highsmith explained how practitioners writing for each other forms a distinct style of writing. He now adds a section to the article with more detail on the craft of how we write in this style. 13 Oct 2026 martinfowler.com
- Naresh Jain compares coding agents with and without a harness. He found it made a frontier model more expensive in tokens for little gain, but make a weaker (and cheaper) model more effective. 13 Oct 2026 martinfowler.com
- Fragments: walking the same path as the Krell, Ola Bini banished, interviewed at DDD Europe with Eric Evans, future of reading code, latest Google model knows less, but pretends less 5 Oct 2026 martinfowler.com
- When slides earn their place they work as a visual channel that complements the speaker rather than replacing them - Sumeet Gayathri Moghe sets out the resulting principles. 30 Sept 2026 martinfowler.com
- Sensible Defaults: do these practices, or do better, and be prepared to explain why you've chosen some other way. 29 Sept 2026 martinfowler.com
- Fragments: agents make programming harder, creating a breakaway agent needs super-persistence, AI needs a conscience more than consciousness, theses on AI regulation 29 Sept 2026 martinfowler.com
- Fragments: the risk from AI is wiring it into everything, colorful syntax highlighting impedes comprehension, what Forward Deployed Engineer should mean 24 Sept 2026 martinfowler.com
- NEW POST Human collaboration improves with feedback, but not obvious to do well. Anuja Karnik and Sumeet Gayathri Moghe pass on a bevy of tips, based on the principle that both praise and criticism should be seen as positive. 24 Sept 2026 martinfowler.com
- NEW POST I see AI and LLMs as bringing a mix of boons and banes, but one feeling dominates: not just are they pretending to be a person, but the kind of person I don't like. 17 Sept 2026 martinfowler.com
- Fragments: two worrying explanations around the RubyGems hack, agents aren't so much super-intelligent as super-persistent, Uncle Bob's harness is obviated, regulation of AI and competition with China 16 Sept 2026 martinfowler.com
- NEW POST Sumeet Gayathri Moghe finds many folks building presentations get tangled in building slides without a coherent narrative. He advises distilling the big idea, visualizing the audience, and building a structured storyline. 15 Sept 2026 martinfowler.com
- NEW POST A quick survey of recent engagement of my posts on social media, indicating which service has by far the most engagement, and which service has seen a precipitous decline since early 2025. 9 Sept 2026 martinfowler.com
- Fragments: dealing with AI's counterfeit utility, exasperated readers of LLMs, missing Creating Passionate Users, agents lack Verum Factum, three people making key decisions on AI 8 Sept 2026 martinfowler.com
- NEW POST Like me, Sumeet Gayathri Moghe is tired of poor presentations with bad slide decks. He's started to write a series of posts on how to avoid these calamities, beginning with a post that questions whether a presentation is needed at all. 8 Sept 2026 martinfowler.com
Link verified 23 Sept 2026. Recent items update automatically from the channel.
Bluesky @martinfowler.com Their Bluesky account.
Recent
- Bliki: One of the curses of the growth of AI is the amount of LLM-Voice I read on the web 29 Oct 2026 martinfowler.com
- Rachel's Ramblings: Why are good developers so wary of agentic development? 29 Oct 2026 martinfowler.com
- Fragments: widening perception gap of LLMs, notes from Foocamp, today is 1997, a shift to supervisory control, Eric Evans keynote, Thoughtworks's token sourcing strategy 28 Oct 2026 martinfowler.com
Show 17 more
- Fragments:LLM generated prose generates rejection, cancellation of Grade Hopper celebration, using AI to assist debugging unfamiliar code 21 Oct 2026 martinfowler.com
- When Kuldeep Singh took on modernizing a huge fleet of IoT sensors, he found that while his engineering principles remained largely the same, he formed a new set of Sensible Defaults for the new environment. 15 Oct 2026 martinfowler.com
- Slide design is based on choices of colors, fonts, and layouts. Sumeet demonstrates how to think about these, and why the best layout is usually a blank one. 14 Oct 2026 martinfowler.com
- A couple of months ago Jim Highsmith explained how practitioners writing for each other forms a distinct style of writing. He now adds a section to the article with more detail on the craft of how we write in this style. 13 Oct 2026 martinfowler.com
- Naresh Jain compares coding agents with and without a harness. He found it made a frontier model more expensive in tokens for little gain, but make a weaker (and cheaper) model more effective. 13 Oct 2026 martinfowler.com
- Fragments: walking the same path as the Krell, Ola Bini banished, interviewed at DDD Europe with Eric Evans, future of reading code, latest Google model knows less, but pretends less 5 Oct 2026 martinfowler.com
- When slides earn their place they work as a visual channel that complements the speaker rather than replacing them - Sumeet Gayathri Moghe sets out the resulting principles. 30 Sept 2026 martinfowler.com
- Sensible Defaults: do these practices, or do better, and be prepared to explain why you've chosen some other way. 29 Sept 2026 martinfowler.com
- Fragments: agents make programming harder, creating a breakaway agent needs super-persistence, AI needs a conscience more than consciousness, theses on AI regulation 29 Sept 2026 martinfowler.com
- Fragments: the risk from AI is wiring it into everything, colorful syntax highlighting impedes comprehension, what Forward Deployed Engineer should mean 24 Sept 2026 martinfowler.com
- NEW POST Human collaboration improves with feedback, but not obvious to do well. Anuja Karnik and Sumeet Gayathri Moghe pass on a bevy of tips, based on the principle that both praise and criticism should be seen as positive. 24 Sept 2026 martinfowler.com
- NEW POST I see AI and LLMs as bringing a mix of boons and banes, but one feeling dominates: not just are they pretending to be a person, but the kind of person I don't like. 17 Sept 2026 martinfowler.com
- Fragments: two worrying explanations around the RubyGems hack, agents aren't so much super-intelligent as super-persistent, Uncle Bob's harness is obviated, regulation of AI and competition with China 16 Sept 2026 martinfowler.com
- NEW POST Sumeet Gayathri Moghe finds many folks building presentations get tangled in building slides without a coherent narrative. He advises distilling the big idea, visualizing the audience, and building a structured storyline. 15 Sept 2026 martinfowler.com
- NEW POST A quick survey of recent engagement of my posts on social media, indicating which service has by far the most engagement, and which service has seen a precipitous decline since early 2025. 9 Sept 2026 martinfowler.com
- Fragments: dealing with AI's counterfeit utility, exasperated readers of LLMs, missing Creating Passionate Users, agents lack Verum Factum, three people making key decisions on AI 8 Sept 2026 martinfowler.com
- NEW POST Like me, Sumeet Gayathri Moghe is tired of poor presentations with bad slide decks. He's started to write a series of posts on how to avoid these calamities, beginning with a post that questions whether a presentation is needed at all. 8 Sept 2026 martinfowler.com
Link verified 23 Sept 2026. Recent items update automatically from the channel.
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