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Rasmus Lerdorf

Summary

Rasmus Lerdorf (born 1968) is a Greenland-born, Canadian-educated programmer who created PHP. He announced its first version, Personal Home Page Tools, on Usenet on June 8, 1995, developed it into PHP/FI, and in 1997 joined Andi Gutmans and Zeev Suraski in building PHP 3, released in June 1998. He has remained a PHP core contributor while working as an engineer at Yahoo, WePay and Etsy.

Web Building Encyclopedia · People · Last reviewed October 22, 2026 · 10 min read

Early life and education

Rasmus Lerdorf was born in 1968 in Qeqertarsuaq (in Danish, Godhavn), a town on Disko Island off the west coast of Greenland.12 His own short biography says he grew up in Denmark and Canada.3 MIT Technology Review noted in 2003 that he had lived in many countries and had learned five languages.2

He studied Systems Design Engineering at the University of Waterloo in Ontario, Canada, and graduated with a bachelor of applied science in 1993.4 The same 2003 profile says he had no formal training in programming.2

His early jobs were in the Toronto area. The Globe and Mail reported that he spent several years at Bell Canada and that PHP began while he was working at the University of Toronto.5

In a 2019 talk he described an internship at Nortel in Toronto. A call-routing system there dropped every waiting call from time to time, and he spent about three and a half months reading printed source code taped to the hallway walls to find out why. The cause was two unrelated parts of the program using the same global variable, a value shared by the whole program.6

He said that bug is the reason PHP makes code inside a function declare when it uses a global variable.6

Personal Home Page Tools, 1994 to 1995

Lerdorf created the first version of PHP in 1994. The PHP project’s own history describes it as a set of Common Gateway Interface (CGI) programs written in the C language. CGI is the standard way for a web server to run an outside program and send that program’s output back as a web page. He first used the tools to track visits to his online resume.7

The project’s sources differ slightly on the very first step. The documentation for PHP/FI 2.0, written in the first person, says PHP started as a small CGI wrapper written in Perl and was later rewritten in C for speed.8 The project’s history page and his 1995 announcement both describe the tools as C programs and do not mention a Perl stage.79

In later talks he explained the idea. He had been writing small C programs for routine webmaster jobs, such as formatting access logs and adding content generated by the server to pages. His plan was a template system whose tags called small C functions that users would write themselves. Users did not want to write C, so they asked him for new tags instead, and he kept writing them.6 He has said it was the Mosaic browser that got him started on the World Wide Web.6

On June 8, 1995, Lerdorf announced the kit on Usenet, a worldwide discussion network older than the web, in the group comp.infosystems.www.authoring.cgi. The post opened: “Announcing the Personal Home Page Tools (PHP Tools) version 1.0.”9

The post described the tools as small CGI programs written in C, offering features that personal pages otherwise could not get without control of the server:9

  • private access logs with a real-time viewer, last-access information, and daily and total access counters;
  • banning or password-protecting visitors by domain, and tracking which pages sent visitors;
  • server-side includes (pieces of a page inserted by the server) on servers that did not support them;
  • forms, with the submitted data usable in other pages such as guestbooks.

The only requirement was permission to run your own CGI programs. No root access, no Perl and no access to the server’s log files were needed. The post said the tools were in the public domain and distributed under the GNU Public License, and it pointed readers to a demonstration page on his io.org account.9

Releasing the source code let other developers use it, report bugs and improve it, the PHP history says.7 The PHP entry covers what the language became after that. This entry follows Lerdorf’s part in it.

From FI to PHP/FI 2.0

In September 1995 Lerdorf expanded the code and, for a short time, dropped the PHP name. The new version, FI (short for Forms Interpreter), had variables that worked like Perl’s, turned form fields into variables automatically and let authors place code inside HTML pages. That code had to be hidden inside HTML comments.7

In October 1995 he released a complete rewrite, briefly called the Personal Home Page Construction Kit. The project’s history says its structure was deliberately modeled on C, so that developers who knew C or Perl could pick it up easily.7

In April 1996 he joined the two names into PHP/FI. This version added built-in support for the DBM, mSQL and Postgres95 databases, cookies and functions defined by users. It was given version 2.0 status in June 1996 and left beta testing in November 1997.7 The PHP/FI 2.0 documentation describes the result as a simple programming language embedded inside HTML files.8

Use spread through 1997 and 1998. The history page cites a Netcraft survey from May 1998 that found nearly 60,000 domains reporting PHP in their web headers, about 1% of all domains at the time. It also names the limit of the project: PHP/FI was still mainly developed by one person.7

Lerdorf has said why the early web hosting business took to it. Other languages ran faster, he said in 2019, but starting a new process for every request made PHP look fast by comparison. He added that security concerns about mod_perl, a way of running Perl inside the Apache server, led internet providers to charge much more for it, while PHP let a provider host about 3,000 customers on one machine.6

PHP 3 and the PHP Group

In 1997 Andi Gutmans and Zeev Suraski, two developers in Tel Aviv, Israel, found PHP/FI 2.0 too slow and limited for an e-commerce application they were building for a university project. They began rewriting its parser, the part of the program that reads and interprets code.7

They contacted Lerdorf online. The three agreed to work together on a new, independent language based on the rewrite, so that it could start with PHP/FI’s existing users. It got a new name, chosen to remove the hint of limited personal use: PHP: Hypertext Preprocessor, a recursive acronym whose first word is the acronym itself.7 The project’s news archive records a vote on April 18, 1998, in which that meaning won with 53% of the votes.10

PHP 3.0 was declared ready for production on June 6, 1998, after 10 months of development, alongside the final release of Apache HTTP Server 1.3.0. The announcement said it was more than twice as fast as PHP/FI 2.0 and used less memory.10 The history page says the new PHP Development Team announced it as the official successor to PHP/FI 2.0, and that it was already installed on more than 70,000 domains.7

Lerdorf has been direct about how much of later PHP he wrote. In a 2002 interview with SitePoint he said: “I did not develop the PHP we know today.” He added that dozens, if not hundreds, of people had developed it.11

The project’s credits page lists ten members of the PHP Group, its core group of developers, among them Lerdorf, Gutmans and Suraski. The same page names Gutmans, Lerdorf, Suraski and Marcus Boerger under language design and concept.12

Core contributor

Lerdorf stayed active in PHP’s development after 1998. In the 2002 SitePoint interview he said he was still quite involved, fixing bugs and arguing with other developers about features.11 In December 2015 he told InfoWorld that he was still involved, mainly with bug fixes.13

PHP’s credits page lists the parts of PHP he wrote or co-wrote:12

  • the CGI and FastCGI server interface, with Stig Bakken, Shane Caraveo and Dmitry Stogov;
  • extensions for EXIF photo data, the GD image library, LDAP directories, SNMP network monitoring, zlib compression and hashing, each with other authors;
  • the Input Filter extension, with Derick Rethans, Pierre-Alain Joye and Ilia Alshanetsky;
  • the php.net websites, as part of the PHP Websites Team.

The filter extension checks or cleans up data, which the manual says is especially useful when the data comes from users.14 It is enabled by default.15 In a 2006 post on his own site, Lerdorf pointed to it as part of keeping a PHP application secure.16

He has also built tools around the language. Phan, a static analyzer that looks for errors in PHP code without running it, carries a 2015 copyright notice in the names of Lerdorf and Andrew Morrison.17 His GitHub profile lists other PHP tools, including opcache-status, a one-page status view for PHP’s built-in code cache.18

His standing in the project also made his name a target. Nikita Popov reported that on March 28, 2021, two malicious commits were pushed to PHP’s source code repository under Lerdorf’s name and his own. The project responded by retiring its own git server, moving to GitHub and requiring two-factor authentication for anyone with write access.19

Career, writing and recognition

MIT Technology Review’s 2003 profile says Lerdorf worked at IBM and Linuxcare before he joined Yahoo in September 2002 to help the company move to PHP-based tools.2 The University of Waterloo also mentions a period working in Brazil.4

At Yahoo he was an infrastructure architect for more than seven years, his biography says.3 The University of Waterloo credits him with creating scanmus, a security tool it calls a key part of Yahoo’s security toolkit.20 TechCrunch reported on November 10, 2009, that he had left Yahoo.21

In April 2010 TechCrunch reported that he had joined WePay, a group payments startup, to lead development of its API, the interface other software uses to connect to a service.22

He then moved to Etsy, the online marketplace. His own biography says he joined in 2011.3 He told Silicon Republic in 2016 that he started as an adviser and that the role grew from there.23 In 2017 the University of Waterloo described him as a Distinguished Engineer at Etsy.20 As of October 2026, his GitHub profile still lists Etsy as his company.18

With Kevin Tatroe he wrote Programming PHP, published by O’Reilly in March 2002.24 O’Reilly’s press release that April described him as PHP’s creator and lead developer and the 507-page book as a guide to PHP 4.25

MIT Technology Review named him to its 2003 list of innovators under 35, at age 34.2 In 2017 the University of Waterloo’s Faculty of Engineering gave him its Alumni Achievement Medal for professional achievement.20

Talks and interviews on PHP’s design

Lerdorf speaks often at conferences, and the PHP project hosts slides for many talks at talks.php.net. His “25 Years of PHP” talk at WeAreDevelopers in Berlin on June 7, 2019, opened with a 1993 form handler written in C and in Perl, followed by the same form in PHP/FI.26 A talk at Etsy in Brooklyn on November 13, 2018, covered PHP 7.2 and 7.3, checking code with Phan and the electricity that could be saved if more servers ran PHP 7.27

Charles Severance interviewed him about the creation of PHP for the IEEE Computer Society’s Computer magazine in 2012.28 Across interviews, several themes recur:

  • A tool for web problems. In 2002 he said PHP “always tries to find the shortest path to solving the Web problem,” and does not try to be a general-purpose scripting language.11
  • Not planned as a language. He told SitePoint that at no point did he think he was writing a scripting language.11 He told InfoWorld in 2015 that he had no idea other people would use it, and that he had built a tool to make dynamic websites faster to create.13
  • Choices made for the early web. In 2019 he said PHP’s function names ignore upper and lower case because web developers were then split over how to write HTML tags, and he did not want to take sides. He said he should have changed this once lowercase tags became the norm.6
  • Compatibility. On PHP 7 he told Silicon Republic that the developers had worked to avoid a split like the one between Python 2 and Python 3, and that decently written PHP 5 code should work in PHP 7.23
  • Performance. He told InfoWorld in December 2015 that most real-world applications would run about twice as fast on PHP 7, and credited Dmitry Stogov, Xinchen Hui and Nikita Popov with driving that work.13 The New Stack reported his 2019 figures for WordPress: about 140MB of memory on PHP 5.3 and about 15MB on PHP 7.3.6

He has argued for keeping PHP applications small. In a 2006 post titled “The no-framework PHP MVC framework,” he advised developers to build a light structure suited to their own needs, aiming at clarity, security and speed, rather than adopting a large framework.16

He describes himself as an engineer more than a programmer. He told Silicon Republic in 2016 that he finds programming tedious and cares about the end product.23 Closing phpDay 2019 in Verona, he said that at every stage he had expected PHP to have about six months of life left.6 The PHP Foundation marked the language’s 30th anniversary on June 8, 2025, dating it to his release of the first version on June 8, 1995.29

Timeline

  1. The PHP Foundation marks 30 years since Lerdorf released the first version29
  2. Malicious commits pushed under Lerdorf's name lead PHP to move its code to GitHub19
  3. Lerdorf gives his "25 Years of PHP" talk in Berlin26
  4. University of Waterloo honors him with its Alumni Achievement Medal20
  5. Joins Etsy, according to his own biography3
  6. Joins WePay to lead development of its API22
  7. Leaves Yahoo21
  8. Named to MIT Technology Review's list of innovators under 352
  9. Joins Yahoo to help it move to PHP-based tools2
  10. O'Reilly publishes Programming PHP, by Lerdorf and Kevin Tatroe24
  11. PHP 3.0, built with Andi Gutmans and Zeev Suraski, is released10
  12. PHP/FI 2.0 leaves beta testing7
  13. Lerdorf introduces PHP/FI7
  14. Lerdorf announces Personal Home Page Tools 1.0 on Usenet9
  15. Graduates in Systems Design Engineering from the University of Waterloo4

What it means for your website

PHP began as a tool Lerdorf wrote for his own home page, and that origin still shows in how most websites are hosted. As of October 22, 2026, W3Techs finds PHP on 69.3% of websites whose server-side language it can detect.30 If your site runs on self-hosted WordPress, it runs on PHP, and we build on WordPress every week.

  • Check your PHP version. Your web hosting control panel usually shows it and lets you change it. WordPress recommends PHP 8.3 or greater.31 As of October 22, 2026, PHP 8.2 receives only security fixes, and those end on December 31, 2026.32 On the same date, W3Techs counts 26.9% of PHP sites still on PHP 7 and 7.7% on PHP 5.30
  • Upgrade for speed and memory, but test first. Lerdorf’s figures for WordPress show memory use falling from about 140MB on PHP 5.3 to about 15MB on PHP 7.3.6 Ask your host or developer to try a new version on a staging site before switching the live one.
  • Keep the code small. His 2006 advice favored small, purpose-built code over large frameworks.16 On a WordPress site, the closest equivalent is to install only the plugins you need and remove the ones you no longer use.
  • Ask how forms check input. PHP’s filter extension, which lists Lerdorf among its authors, validates or cleans up data that visitors type.1214 If a developer builds a custom form for you, ask how its input is checked.

Our WordPress review covers what to ask a host about PHP before you sign up.

See also

References

  1. Speaker biography: Rasmus Lerdorf. Southern California Linux Expo (SCALE) 2002. 2002. accessed October 22, 2026.
  2. Rasmus Lerdorf, 34 (Innovators Under 35, 2003). MIT Technology Review. 2003-10-01. accessed October 22, 2026.
  3. Bio. Rasmus Lerdorf, lerdorf.com. accessed October 22, 2026.
  4. Distinguished Alumni Seminar: "From Waterloo to Etsy via Brazil and how PHP happened along the way" by Rasmus Lerdorf. Faculty of Engineering, University of Waterloo. 2017-11-15. accessed October 22, 2026.
  5. Popular PHP is hot, and it's Canadian. The Globe and Mail. accessed October 22, 2026.
  6. PHP Creator Rasmus Lerdorf Shares Lessons Learned from the Last 25 Years. David Cassel, The New Stack. 2019-09-08. accessed October 22, 2026.
  7. History of PHP. PHP Manual, The PHP Group. accessed October 22, 2026.
  8. PHP/FI Version 2.0 Documentation. The PHP Group, php.net. accessed October 22, 2026.
  9. Announce: Personal Home Page Tools (PHP Tools). Rasmus Lerdorf, comp.infosystems.www.authoring.cgi (Usenet), Google Groups archive. 1995-06-08. accessed October 22, 2026.
  10. PHP news archive, 1998. The PHP Group, php.net. 1998. accessed October 22, 2026.
  11. PHP's Creator, Rasmus Lerdorf. Kevin Yank, SitePoint. 2002-05-22. accessed October 22, 2026.
  12. PHP Credits. The PHP Group, php.net. accessed October 22, 2026.
  13. PHP 7 offers twice the performance. Paul Krill, InfoWorld. 2015-12-04. accessed October 22, 2026.
  14. Introduction: Data Filtering. PHP Manual, The PHP Group. accessed October 22, 2026.
  15. Data Filtering: Installation. PHP Manual, The PHP Group. accessed October 22, 2026.
  16. The no-framework PHP MVC framework. Rasmus Lerdorf, Rasmus' Toys (toys.lerdorf.com). 2006-02-27. accessed October 22, 2026.
  17. Phan license (LICENSE). phan/phan repository, GitHub. accessed October 22, 2026.
  18. rlerdorf (Rasmus Lerdorf). GitHub. accessed October 22, 2026.
  19. Changes to Git commit workflow. Nikita Popov, php.internals mailing list. 2021-03-28. accessed October 22, 2026.
  20. Faculty of Engineering 2017 Alumni Achievement Medal. Systems Design Engineering, University of Waterloo. 2017-11-15. accessed October 22, 2026.
  21. PHP Founder Rasmus Lerdorf Leaves Yahoo. Nik Cubrilovic, TechCrunch. 2009-11-10. accessed October 22, 2026.
  22. PHP Founder Rasmus Lerdorf Joins Group Payments Startup WePay. Jason Kincaid, TechCrunch. 2010-04-27. accessed October 22, 2026.
  23. Rasmus Lerdorf, father of PHP: Programming is boring. Gordon Hunt, Silicon Republic. 2016-01-13. accessed October 22, 2026.
  24. Programming PHP. Rasmus Lerdorf and Kevin Tatroe, O'Reilly Media. 2002-03. accessed October 22, 2026.
  25. O'Reilly's Much Anticipated "Programming PHP" Offers Mastery of the Language for Web Authors. O'Reilly Media. 2002-04-25. accessed October 22, 2026.
  26. 25 Years of PHP (WeAreDevelopers, Berlin). Rasmus Lerdorf, PHP Presentation System, talks.php.net. 2019-06-07. accessed October 22, 2026.
  27. PHP in 2018 (Code as Craft, Etsy, Brooklyn). Rasmus Lerdorf, PHP Presentation System, talks.php.net. 2018-11-13. accessed October 22, 2026.
  28. Inventing PHP: Rasmus Lerdorf. Charles Severance, Computer (IEEE Computer Society). 2012-12-12. accessed October 22, 2026.
  29. 30 years of PHP: FrankenPHP is now part of the PHP organisation. Roman Pronskiy, The PHP Foundation. 2025-06-08. accessed October 22, 2026.
  30. Usage statistics and market share of PHP for websites. W3Techs. 2026-10-22. accessed October 22, 2026.
  31. Requirements. WordPress.org. accessed October 22, 2026.
  32. Supported Versions. The PHP Group, php.net. accessed October 22, 2026.

Web Building Encyclopedia. First published October 22, 2026. Last reviewed October 22, 2026. Every fact on this page is linked to a source we opened. Spotted an error? Write to [email protected].