Esteve Castells Calpe, professionally known as Esteve Castells, is an independent search engine optimization (SEO) consultant, growth advisor, and entrepreneur. He led global SEO at Adevinta and co-founded LLM Pulse, a platform for measuring how brands appear in AI-generated answers. His work spans technical SEO, international marketplaces, and software for search and domain analysis.[1][3][9][13]

Castells’s career took him through Havas Media and Softonic before he joined Adevinta in 2019. He moved into full-time independent consulting in 2024. Alongside consulting, he writes the Spanish-language newsletter Seopatía, teaches SEO, and publishes browser extensions and open-source tools.[4][12]

His public work includes a contribution to the Next.js SEO course, talks at BrightonSEO and Spanish search-industry events, and DomScan, an API for domain and internet intelligence.[18][25][2]

Education and early projects

Castells studied Marketing and Digital Communities at TecnoCampus, a university centre affiliated with Pompeu Fabra University. The institution’s faculty directory lists his degree and identifies his professional interests as SEO, data analysis, growth, and product management.[3]

In a November 2024 interview with ChuletaSEO, he traced his interest in SEO to a university conversation about growth hacking. He began learning independently through websites and blogs of his own, treating them as experiments. He also described taking an internship during his first university year and combining employment with his studies.[4]

In November 2015, he was part of the five-person team that won TecnoCampus’s Weekend Challenge entrepreneurship competition. Their proposal, E-center, was a digital leisure venue inspired by professional esports, combining competitive gaming with teamwork and social interaction. The university named Castells alongside Eduard Álvarez, Martín Bellido, Álex Muñoz, and Gerard Xalabardé.[5]

SEO career

Havas Media and Softonic

TecnoCampus’s academic reports document Castells’s early professional roles: the 2016–17 report identifies him as an SEO specialist at Havas Media, and the 2017–18 report lists him as an international SEO specialist at Softonic. His later interview accounts describe the same progression from agency work to a large software-publishing website.[6][7][4]

A professional profile published by Zyppy describes his Havas responsibilities as technical auditing and client account management, and his Softonic role as spanning international SEO and performance marketing. The profile credits him with a multilingual tag-page initiative that reached more than 300,000 daily visits over fifteen months; this is a reported professional achievement, rather than an independently audited result.[8]

Adevinta, 2019–2024

According to his public professional profile, Castells joined Adevinta as Global SEO Manager in January 2019, holding that position until June 2021. He became Global Head of SEO in July 2021 and remained in the role until April 2024.[9]

He describes a remit that included international strategy, recruiting, coordination between local marketplaces, and integrating SEO teams following Adevinta’s combination with eBay Classifieds Group. His profile reports moving SEO roles from marketing into product, leading a 13-person global team, and contributing to the SEO roadmap for the Polaris platform. The marketplaces named include Fotocasa, Marktplaats, Coches.net, Subito, Milanuncios, Willhaben, and DoneDeal.[9]

His December 2019 Clinic SEO presentation documented the organisational side of that work: obtaining management support, establishing local ownership, securing product and engineering resources, and improving understanding of SEO across the group. The presentation also explored machine-learning applications in search optimization.[10]

A March 2023 interview with Marketing Paradise identified him as Adevinta’s Global Head of SEO and examined how search work fits inside a large marketplace business. Topics included internal linking, user-generated content, conversion optimization, user experience, and AI.[11]

Independent consulting, 2024 onward

Castells publicly announced his move to full-time independent consulting in September 2024. In the announcement, he explained that he had already been working independently for several months and had left Adevinta by 1 May. He described a practice extending beyond SEO into product, AI, market research, growth, and marketing.[12]

The same announcement introduced a redesigned personal website, a move from Medium to his own blog, browser extensions, and a collection of twenty free online tools. His November 2024 interview described strategic and technical SEO as central to his consulting work.[12][4]

RentasPasivas.com also lists Castells as its chief technology officer, with responsibility for technology development, SEO strategy, and the evolution of the platform.[17]

LLM Pulse

Castells co-founded LLM Pulse with Daniel Peris and Adrian Rojas. According to the company’s history, the idea emerged in January 2025 from a discussion with consulting client YunoJuno about measuring visibility in AI search. An initial development attempt stalled; Castells resumed the project with Peris in May, and Rojas joined to lead development.[13]

The service launched in July 2025. It tracks brand mentions, citations, and sentiment in AI-generated answers, including responses from ChatGPT, Perplexity, and Google’s AI search products. The company describes itself as bootstrapped and reported passing one hundred customers by December 2025.[13]

Its first-anniversary article, published in July 2026, identifies Castells as co-CEO and co-founder. It describes the product’s expansion from a ChatGPT tracker into a broader AI visibility platform, with prompt research, comparisons across models, citation analysis, testing, agency features, and integrations. The company also introduced Tremor, a free weekly tracker of volatility in AI search results.[14]

In September 2026, LLM Pulse announced a ChatGPT app for querying account data from within ChatGPT. The company said the app had been approved for distribution; OpenAI’s public listing names LLM PULSE SL as its developer.[44] A 20 September report by Periodismo Digital covered LLM Pulse’s ranking of Spanish news outlets cited by AI answers and quoted Castells distinguishing source presence from audience and influence.[45]

A July 2026 customer story from ChartMogul reported that LLM Pulse had reached hundreds of customers while retaining a three-person team and operating without external funding. The interview discussed customer feedback, AI-assisted software development, and subscription metrics. As a supplier’s customer story, it provides an external account with an existing commercial relationship to the company.[15]

A 30 September 2026 report by EL ESPAÑOL named Castells among LLM Pulse’s founders and reported that the company had more than 50 customers in the United States. It also named Holafly, Metricool, iLovePDF, Softonic, and Adevinta among its clients.[52]

Software and tools

DomScan

DomScan is another of Castells’s publicly listed products. Its API brings together domain availability, WHOIS and RDAP registration data, DNS, certificates, website information, and monitoring. The product is aimed at developers and AI agents, with a command-line client, software development kits, and a Model Context Protocol (MCP) integration.[2][16]

Open-source projects and browser utilities

Castells’s public GitHub profile presents his software work as an extension of his interests in search, AI visibility, and domains. It lists OpenAdScan, a self-hosted tool for brand and search-marketing intelligence; the official DomScan CLI and SDKs; and an uptime-monitoring project built for Cloudflare Workers.[2]

Earlier utilities announced in 2024 included SEO Robots Inspector and Google Calendar Blur Events Name, as well as tools for exporting Knowledge Graph entities and working with language models in Google Sheets.[12]

Chrome Web Store listings identify him as the developer of SEO X-Ray and RoboView, an extension for visualizing robots.txt crawler-access rules. His uptime-monitoring repository provides website checks, incident history, and notifications under the MIT licence; the DomScan SDK repository provides clients for multiple programming languages.[37][38][39][40]

Teaching

The official Next.js Learn course on SEO and Core Web Vitals acknowledges Gary Meehan and Esteve Castells for helping create it. The credit documents his contribution to developer education on the framework’s own website.[18]

Castells appears in the public faculty directories of TecnoCampus and Webpositer Academy. A 2023 programme for KSchool’s professional SEO-SEM master’s, offered through the Chamber of Commerce of Murcia, lists him among its instructors. VisibilidadOn lists him among the faculty for its 2026 SEO/GEO master’s; the provider’s page described the October start as planned.[3][19][20][48]

His own media archive additionally records teaching appearances at UPF Barcelona School of Management, the University of Granada, and online SEO training platforms.[41]

Participation in academic research

Castells contributed an expert interview to SEO y Periodismo, a 2020 report by Carlos Lopezosa, Lluís Codina, and Carlos Gonzalo-Penela, published through Pompeu Fabra University. His interview discusses ranking factors, semantic search, voice search, and search intent in the context of digital journalism.[42]

He was also one of 32 experts interviewed for a study of voice-search optimization in digital media, published in Profesional de la información in 2023. The study, by Carlos Lopezosa, Lluís Codina, Javier Guallar, and Mario Pérez-Montoro, identifies him in its SEO consultancy group; the interviews took place in early 2022.[43]

Writing and Seopatía

Seopatía

Castells began publishing Seopatía in 2017. The Spanish-language newsletter combines commentary with curated links about SEO, marketing, technology, and digital business. Its public description reported more than 3,700 subscribers when accessed on 5 October 2026.[21]

In 2022, researchers Jesús-Daniel Cascón-Katchadourian, Juan-José Boté-Vericad, and Javier Guallar included Seopatía in an academic study of ten independent Spanish newsletters, published in Ibersid. Their dataset recorded a launch date of August 2017 and 2,795 subscribers in June 2021. The study examined newsletters as a form of information curation associated with an individual author.[22]

Seopatía reached its 100th issue on 13 October 2022. In that edition, Castells reflected on more than five years of publication and the changing demands of maintaining the newsletter alongside his professional responsibilities.[23]

Articles and essays

His published writing predates the newsletter. In December 2015, Psicología y Mente published his article on reciprocity, popularity, and unwritten conventions in social networks. A January 2016 column in MarketingDirecto discussed product differentiation through the ideas in Seth Godin’s Purple Cow. Both articles were signed Esteve Castells Calpe.[24][31]

Later writing focuses on technical SEO, AI-assisted work, and changes in how people find information. Selected essays include:

  • “How AI breakthroughs turbocharged my day-to-day as an SEO” (23 October 2023), an account of using ChatGPT to expand the work he could implement independently.[32]
  • “The truth about the future of SEO” (3 November 2024), which argues that AI may expand demand for information while reducing the share of searches that lead to website visits. It also considers publisher compensation and increasingly similar online content.[33]
  • “AI, Aggregation and the Great Re-Sorting: Why LLMs Are Your New Front-End” (16 June 2025), an examination of language models as an interface between users, websites, services, and marketplaces.[34]
  • “The Spanish media groups with the highest AI visibility” (9 July 2026), an analysis of publishing groups cited in AI answers, using aggregate LLM Pulse data.[35]
  • “Agentic Marketing: What These Agents Can Actually Do” (20 September 2026), a discussion of how to distinguish systems that execute marketing actions from tools that provide assistance.[46]
  • “How to Measure AI Visibility Without Fooling Yourself” (27 September 2026), which sets out a repeated-sample approach and discusses limits on interpreting AI visibility measurements.[47]
  • “Visibilidad en IA: ¿cambió todo o no cambió nada?” (2026), an article about AI visibility measurement that recounts his Buenos Aires session and an analysis of 644,291 citations across 2,722 prompts configured for Argentina and five AI search surfaces. The article notes that its dataset skews towards commercial topics.[51]

Talks and interviews

Castells’s public presentations cover website migrations, web scraping, developer implementation, and the organisation of SEO within large businesses. His published slides and event reporting document a progression from hands-on technical subjects to international team coordination and AI-assisted work.[27][10][28]

Selected public appearances
YearEvent or programmeSubject
2018Comunidad SEO GaliciaSEO para Desarrolladores Web: practical SEO implementation for developers.[27]
2018SEOplus, AlicanteAdvanced web scraping, presented with Nacho Mascort.[26]
2018BrightonSEOLessons from migrating 100,000 subdomains to subfolders.[25]
2019Clinic SEO, BarcelonaBuilding SEO capabilities across Adevinta and connecting the work to product and engineering.[10]
2023Paradisers, Marketing ParadiseSEO in large portals, internal linking, user experience, and conversion optimization.[11]
2023The Inbound, episode 3Whether SEO belongs in product or marketing; obtaining support for projects; building a specialist newsletter.[29]
2023SEO, automatización & AI en grandes portalesAutomation and AI applications in large websites; slides published 2 October 2023.[28]
2025VisibilidadOn, episode 117Measuring visibility in ChatGPT and other language models; published 17 December 2025.[30]
2026Eleven Session, Buenos AiresTalk on measuring AI visibility, followed by a panel discussion.[49][50][51]

His public media archive brings together further podcast appearances, guest articles, courses, and conference materials. It provides a wider catalogue of his published work, although it is maintained by Castells himself.[41]

Search research and professional ideas

SEO as an organisational practice

A recurring theme in Castells’s work is that SEO depends on an organisation’s ability to implement recommendations. His Adevinta presentation describes responsibilities spread across product, technology, content supply, and brand, with local ownership and management support needed to carry out changes. His later interviews return to the relationship between specialist search teams and the wider business.[10][29]

Measuring visibility in AI answers

His writing on AI discovery distinguishes being visible in generated answers from receiving a visit to a website. In an LLM Pulse article on AI rank tracking, he argues for measuring patterns across prompts and responses rather than treating an individual generated answer as a stable search ranking. These positions reflect both his consulting work and his role in an AI visibility measurement company.[36]

His July 2026 Spanish-media study examined 743,259 AI answers containing sources, gathered between 10 April and 8 July 2026 for prompts configured for Spain and Spanish. It compared 82 media domains grouped by publisher. PRISA had the highest citation visibility among the groups in that sample, with substantial variation between models.[35]

The article limits its findings to the selected domains and the LLM Pulse sample. Castells explicitly separates the observed citation patterns from a claim that publisher agreements caused them, and discusses crawling access, content characteristics, and model differences as possible factors.[35]

Selected chronology

DateMilestone
2015Member of the E-center team that wins TecnoCampus’s Weekend Challenge; publishes an article in Psicología y Mente.[5][24]
2016–2018University records document SEO roles at Havas Media and Softonic.[6][7]
2017Begins publishing Seopatía.[22]
2018Presents at BrightonSEO and SEOplus.[25][26]
January 2019Joins Adevinta as Global SEO Manager.[9]
July 2021Becomes Global Head of SEO at Adevinta.[9]
October 2022Publishes Seopatía’s 100th issue.[23]
2024Leaves Adevinta and moves into full-time independent consulting.[12]
July 2025Launches LLM Pulse with Daniel Peris and Adrian Rojas.[13]
July 2026LLM Pulse marks its first anniversary; ChartMogul profiles its three-person team and hundreds of customers.[14][15]

References

Sources checked 5 October 2026. Labels distinguish first-party accounts from external publications.

  1. Personal website Castells, Esteve. “About Esteve Castells.” Biography and public photographs.
  2. Public profile Castells, Esteve. GitHub profile and project directory.
  3. University TecnoCampus. “Esteve Castells Calpe.” Faculty profile.
  4. Interview Rodríguez García, Emilio. “Esteve Castells – Entrevista SEO.” ChuletaSEO, 13 November 2024.
  5. University news TecnoCampus. Report on the E-center team’s Weekend Challenge 2015 win. 17 November 2015.
  6. University report TecnoCampus. Academic report, 2016–2017. PDF; identifies Castells’s Havas Media role.
  7. University report TecnoCampus. Academic report, 2017–2018. PDF; identifies his Softonic role.
  8. Professional directory Zyppy. “Esteve Castells.” Profile updated 7 April 2025.
  9. Self-reported profile Castells, Esteve. Public Malt profile. Employment dates and responsibilities.
  10. Speaker slides Castells, Esteve. “Cómo estamos transformando el SEO en Adevinta de 0 a 100.” Clinic SEO Barcelona, 17 December 2019.
  11. Interview Marketing Paradise. Interview with Esteve Castells. 28 March 2023.
  12. First-person account Castells, Esteve. “Seopatía #102: Metamorfosis profesional.” 17 September 2024.
  13. Company history LLM Pulse. “About Us.” Founders, origins, and milestones.
  14. Company publication Peris, Daniel. “One Year of LLM Pulse.” 15 July 2026; updated 28 August 2026.
  15. Supplier customer story ChartMogul. “Why LLM Pulse trusts ChartMogul over in-house subscription analytics.” 31 July 2026.
  16. Product website DomScan. Product catalogue and public documentation.
  17. Company team page RentasPasivas.com. “Nuestro equipo.”
  18. Course publisher Next.js. “Next Steps.” SEO and Core Web Vitals course acknowledgements.
  19. Education provider Webpositer Academy. Faculty directory.
  20. Chamber of commerce course listing Cámara de Comercio de Murcia. “Máster en SEO-SEM Profesional.” KSchool programme, seventh edition, beginning 7 November 2023; faculty list.
  21. Publication’s own account Seopatía. About the newsletter. Audience figure checked 5 October 2026.
  22. Academic study Cascón-Katchadourian, Jesús-Daniel; Boté-Vericad, Juan-José; Guallar, Javier. “Curación de información con marca de autor: análisis de newsletters independientes.” Ibersid 16(1), 2022, pp. 41–53. Open-access PDF, Table II.
  23. First-person account Castells, Esteve. “Seopatía #100: ¡Y... Cien!” 13 October 2022.
  24. Authored article Castells Calpe, Esteve. “La psicología detrás de las redes sociales: el código de comportamiento no escrito.” Psicología y Mente, 30 December 2015.
  25. Conference recap SDIM. BrightonSEO recap, 28 September 2018. Coverage of Castells’s subdomain-migration talk.
  26. Event reporting MarketingDirecto. Report on the SEOplus web-scraping session. 30 July 2018.
  27. Speaker slides Castells, Esteve. “SEO para Desarrolladores Web (Guía).” Comunidad SEO Galicia, uploaded 16 February 2018.
  28. Speaker slides Castells, Esteve. “SEO, automatización & AI en grandes portales.” Uploaded 2 October 2023.
  29. Podcast listing The Inbound Podcast. “¿SEO en Producto o Marketing? Enterprise SEO y Newsletters – Esteve Castells.” 16 August 2023, listed in the programme feed.
  30. Podcast interview VisibilidadOn. Episode 117, interview with Esteve Castells. 17 December 2025.
  31. Authored column Castells Calpe, Esteve. “La clave para diferenciarte de tu competencia y triunfar.” MarketingDirecto, 20 January 2016.
  32. Personal essay Castells, Esteve. “How AI breakthroughs turbocharged my day-to-day as an SEO.” 23 October 2023.
  33. Personal essay Castells, Esteve. Essay on the future of SEO. 3 November 2024.
  34. Personal essay Castells, Esteve. Essay on AI aggregation and LLMs as a front end. 16 June 2025.
  35. Author’s data study Castells, Esteve. “The Spanish media groups with the highest AI visibility.” 9 July 2026.
  36. Company publication Castells, Esteve. “AI Rank Tracking Myths: What critics get wrong about measuring visibility in LLMs.” 12 June 2026; updated 10 August 2026.
  37. Software listing Chrome Web Store. SEO X-Ray. Extension and developer listing.
  38. Software listing Chrome Web Store. RoboView. Extension and developer listing.
  39. Public repository Castells, Esteve. Uptime Monitoring Workers. Source, README, and licence.
  40. Public repository Castells, Esteve. DomScan SDKs.
  41. Personal catalogue Castells, Esteve. “Media Compilation.” Talks, interviews, articles, and teaching.
  42. Academic report Lopezosa, Carlos; Codina, Lluís; Gonzalo-Penela, Carlos. “SEO y Periodismo: Marco de optimización global como parte del emprendimiento en cibermedios.” UPF / DigiDoc, May 2020. Interview, printed p. 60. University publication announcement.
  43. Academic study Lopezosa, Carlos; Codina, Lluís; Guallar, Javier; Pérez-Montoro, Mario. “Voice search optimization in digital media: challenges, use and training.” Profesional de la información 32(3), e320307, 9 May 2023. Participant table, p. 4.
  44. Company announcement and official app listing LLM Pulse. Announcement of its ChatGPT app approval. September 2026. OpenAI’s ChatGPT listing identifies LLM PULSE SL as the developer.
  45. Independent publication, company data Pellicer, Miquel. “Los medios españoles más citados por la IA.” Periodismo Digital, 20 September 2026. The article quotes Castells and describes an LLM Pulse ranking; see also the company’s public data-studies page.
  46. Company publication Castells, Esteve. “Agentic Marketing: What These Agents Can Actually Do.” LLM Pulse, 20 September 2026.
  47. Company publication Castells, Esteve. “How to Measure AI Visibility Without Fooling Yourself.” LLM Pulse, 27 September 2026.
  48. Education provider, scheduled 2026 programme VisibilidadOn. “Máster consultor SEO y GEO edición 2026.” Faculty roster; edition planned to begin in October 2026.
  49. First-person event announcement Castells, Esteve. LinkedIn announcement of his planned 21 July 2026 appearance at Eleven’s “Visibilidad en IA” session in Buenos Aires.
  50. Event host Eleven. Post-event summary of the “Visibilidad en IA” session. LinkedIn, 2026.
  51. First-person account and company-hosted analysis Castells, Esteve. “Visibilidad en IA: ¿cambió todo o no cambió nada?” Eleven blog, 2026. Argentine prompt and citation analysis; the page does not display a publication date.
  52. Independent news report B. A. “Medir y optimizar la visibilidad de las marcas en la IA: la tecnología española que desafía a los gigantes de Silicon Valley.” EL ESPAÑOL, 30 September 2026; updated 30 September 2026.

About this page

This article brings together publicly available professional information. Company pages, interviews, and personal writing are identified as such; they provide evidence of roles, projects, and stated views. They do not imply independent verification of every commercial claim. Private files, correspondence, and account data were not used.

The format was inspired by Javi Santana’s Wikipedia-style biography. This page is a personal-site article, with no affiliation to Wikipedia or the Wikimedia Foundation.

Topics: Search engine optimizationEntrepreneurshipSoftwareWritingEducation