--- title: "Optimizing for Gemini vs ChatGPT in Singapore: what actually differs" excerpt: "Gemini answers from Google Search, while ChatGPT's search has used Bing as its default since 2023 and adds its own crawler. In Singapore, where Bing has under 5% of search, that gap is easy to miss. Here is what differs, from crawlers to citations, and the fixes that work for both." date: 2026-10-19 author: GeoVector readTime: 11 min read category: guide tags: [] --- # Optimizing for Gemini vs ChatGPT in Singapore: what actually differs Gemini and ChatGPT find your pages through different search systems. Gemini grounds its answers in Google Search.[^fn-1] ChatGPT's search has used Bing as its default since May 2023,[^fn-2] and OpenAI runs its own search crawler, OAI-SearchBot, on top of that.[^fn-3] So the work splits three ways: the index you rank in, the crawler you let in, and the outside sources you appear on. In Singapore that split is sharper than in most markets. Google held 92.16% of local search in September 2026 and Bing held 4.53%,[^fn-4] so Bing is easy to overlook. Everything else (clear entity details, answer-first pages, sourced numbers) serves both engines at once. GeoVector tracks Gemini and ChatGPT side by side with four other AI assistants, so you can see which engine is skipping you before you rebuild anything. ## Gemini vs ChatGPT at a glance | Factor | Gemini | ChatGPT | | --- | --- | --- | | Where live answers come from | Google Search grounding[^fn-1] | Bing as default search, since May 2023[^fn-2] | | Crawler that decides access | Googlebot for Search; Google-Extended for Gemini Apps grounding and training[^fn-5] | OAI-SearchBot for search; GPTBot for training only[^fn-3] | | Domains cited per answer (Yozigo, June to September 2026) | 3.5[^fn-6] | 9.5[^fn-6] | | Median overlap with Google's top 10 (Chen et al., 1,000 queries) | 8.5% for Gemini 2.5 Flash[^fn-7] | 0.0% for web-enabled GPT-4o[^fn-7] | | Brand's own site cited in unbranded answers (Yozigo) | 6.0%[^fn-6] | 7.9%[^fn-6] | | First move for a Singapore business | Google Search Console and Google Business Profile | Bing Webmaster Tools and Bing Places | The last row is our recommendation, not a measurement. The rest of this guide explains each row and what to do about it. ## Gemini answers from Google's index When Gemini decides a search would help, it writes one or more queries, runs them on Google, and ties each part of its reply to a source URL.[^fn-1] Google's AI Overviews and AI Mode draw on the same index. To appear as a supporting link there, a page only has to be indexed and eligible to show a snippet in Google Search.[^fn-8] That makes Gemini sound like ordinary SEO. It is close, but not identical. Google says both AI features can use "query fan-out", which runs several related searches across subtopics before writing a response.[^fn-8] Your page can rank well for the head term and still miss the sub-questions Gemini actually searched. The numbers bear this out. Chen and colleagues compared AI answers with Google results across 1,000 ranking-style queries. Gemini 2.5 Flash, grounded in Google Search, had a median domain overlap of only 8.5% with Google's top 10.[^fn-7] Ranking on Google helps, but it does not guarantee a citation. One setting trips up a lot of sites. Google-Extended is the robots.txt token that controls whether your content is used to train Gemini and to ground answers in Gemini Apps.[^fn-5] Google states that it does not affect inclusion or ranking in Google Search.[^fn-5] Block it, and you can rank on Google, appear in AI Overviews, and still be missing from the Gemini app. ## ChatGPT answers from Bing and its own crawler Microsoft announced Bing as "the default search experience" in ChatGPT in May 2023.[^fn-2] OpenAI also crawls the web itself. Its documentation says OAI-SearchBot "is used to surface websites in search results in ChatGPT's search features", and recommends allowing it in robots.txt.[^fn-3] Do not confuse it with GPTBot. GPTBot collects training data, so blocking it keeps you out of model training but not out of ChatGPT search.[^fn-3] OpenAI notes that robots.txt changes take about 24 hours to apply.[^fn-3] Google rankings tell you very little here. In the same 1,000-query study, web-enabled GPT-4o had a mean overlap of 4.0% with Google's top 10 and a median of 0.0%.[^fn-7] For more than half the queries, not one cited domain appeared in Google's top 10.[^fn-7] ChatGPT also spreads its citations wider. Yozigo, a GEO platform, ran the same prompts daily for 37 brands from 29 June to 27 September 2026. ChatGPT cited 9.5 domains per answer and Gemini cited 3.5.[^fn-6] More slots means more chances to appear, and more rivals sharing each answer. Yozigo's advice for ChatGPT is broad coverage across comparison pages and lists.[^fn-6] ## Why the Bing gap matters most in Singapore Skipping Bing in Singapore looks sensible: at 4.53% of local search, it sends little traffic.[^fn-4] ChatGPT is a different story. OpenAI's Oliver Jay said Singapore "consistently ranked as one of the highest per capita ChatGPT usage globally", in remarks reported by the Economic Development Board in May 2026.[^fn-9] Your buyers are on ChatGPT even if they never open Bing. So the cheapest fix for ChatGPT visibility in Singapore is often a Bing fix. Verify your site in [Bing Webmaster Tools](https://www.bing.com/webmasters/about), submit your sitemap, and check that your key service pages are indexed. Then claim your listing on [Bing Places](https://www.bingplaces.com/), which is Bing's version of a business profile. Both are free. Crawler access is rarely the blocker locally. SingRank checked 219 Singapore service-business websites on 25 September 2026 and found that only 1 of 207 working robots.txt files blocked GPTBot and ClaudeBot.[^fn-10] That study did not test OAI-SearchBot or Google-Extended, though. Check those two on your own domain with GeoVector's free [AI crawler checker](https://www.geovector.ai/tools/ai-crawler-checker), which tests 11 AI user agents with no sign-up. ## Fix the entity details both engines read Both engines lean heavily on what other sites say about you. In Yozigo's data, third-party sites made up 83.0% of Gemini's citations.[^fn-6] A brand's own site was cited in only 6.0% of Gemini's unbranded answers and 7.9% of ChatGPT's.[^fn-6] Directories, reviews and comparison pages carry most of the weight. Those sources need to describe the same business. Google's rule for Business Profiles is to represent your business as it is "consistently represented and recognized in the real world".[^fn-11] In Singapore, that usually means choosing between your ACRA-registered name and your trading name, then using one form everywhere. Run this check across your website, Google Business Profile, Bing Places and the local directories you appear on: - **Name:** the same business name in the same form on every listing. - **Address:** one format, including the unit number and postal code. - **Phone and website:** one main number and one canonical URL. - **What you do:** the same one-line description of your services and the areas you serve. - **Identifiers:** your UEN on your own site, so a reader can match you to the ACRA record. Then give each page local detail that a London or Sydney page cannot copy. Name the districts and MRT stations you cover, the Singapore rules that apply to your service, and your prices in SGD. A generic English page reads the same as a page from any other English-speaking market. ## Write one page that both engines can quote You do not need a separate page for each engine. Google says there is no special [schema.org](https://schema.org) markup, AI text file or machine-readable file required to appear in AI Overviews or AI Mode.[^fn-8] Structured data still helps Google understand a page, but it is not a Gemini switch. What moves both engines is content they can lift and trust. In the original GEO research by Aggarwal and colleagues, published at KDD 2024, adding citations, quotations and statistics lifted visibility by up to 40% in generative engine responses.[^fn-12] Write for that: 1. **Answer first.** Open each section with the direct answer, then the detail. 2. **Use real numbers.** Prices in SGD, timeframes, and service limits, each with a source or a date. 3. **Make sections stand alone.** A heading that matches the question, and a short block that still makes sense when quoted on its own. 4. **Add a comparison table** where buyers compare options. ChatGPT's wide citation pattern favours comparison pages and lists.[^fn-6] 5. **Get onto other sites.** Earn mentions on local directories, review platforms and industry round-ups, because that is where most citations land.[^fn-6] ## Measure each engine on its own Start with referral traffic. Visits from Gemini arrive as [gemini.google.com](https://gemini.google.com) in your analytics, and visits from ChatGPT arrive as [chatgpt.com](https://chatgpt.com).[^fn-13] Report them as two channels, not one "AI" bucket, because their causes and fixes differ. Referrals only count clicks, and many AI answers never earn one. To see whether you are named at all, run the same prompts on both engines over several weeks and compare. GeoVector does this across 6 AI assistants: ChatGPT, Gemini, Claude, Perplexity, Google AI Overview and Google AI Mode.[^fn-14] It reports weekly brand share by engine and scores every cited URL as owned, earned or an outreach opportunity.[^fn-14] That view answers the question this guide raises: which engine is skipping you, and which sources does it cite instead. If Gemini names you and ChatGPT does not, start with Bing and the comparison pages ChatGPT cites. If it is the other way round, start with Google-Extended, query fan-out and your Google Business Profile. See your AI visibility by engine before you spend on either. ## Frequently asked questions ### Is optimizing for Gemini the same as SEO for Google? Mostly, but not fully. Gemini grounds answers in Google Search, so indexing and snippet eligibility come first.[^fn-1][^fn-8] Yet Gemini 2.5 Flash had only an 8.5% median overlap with Google's top 10 across 1,000 queries,[^fn-7] because fan-out searches sub-questions your page may not answer.[^fn-8] ### Does blocking GPTBot remove my site from ChatGPT? No. GPTBot gathers training data. OAI-SearchBot is the crawler that surfaces sites in ChatGPT search, and OpenAI recommends allowing it.[^fn-3] Check both in your robots.txt, and allow about 24 hours for changes to apply.[^fn-3] ### Do I need llms.txt or special schema to appear in Google's AI answers? Google says no. There are no extra technical requirements, no special [schema.org](https://schema.org) markup and no AI text files needed for AI Overviews or AI Mode.[^fn-8] Focus on being indexed, snippet-eligible and clearly written. ### Should a Singapore business bother with Bing? Yes, if ChatGPT matters to you. Bing has 4.53% of Singapore search,[^fn-4] but it has been ChatGPT's default search since 2023.[^fn-2] Setting up Bing Webmaster Tools and Bing Places is free. ### Which engine should I prioritize first? The one your buyers use and you currently lose. Measure brand share for the same prompts on each engine, then fix the gap that costs you most. A weekly cross-engine tracker such as GeoVector shows this without manual testing.[^fn-14] ## Related reading - [How to choose a GEO platform for ChatGPT, Gemini and Perplexity](https://www.geovector.ai/articles/how-to-choose-a-geo-platform-chatgpt-gemini-and-perplexity): seven questions to ask any vendor before you buy. - [Why AI assistants ignore your Singapore business](https://www.geovector.ai/articles/singapore-business-not-showing-in-ai-answers): the common causes and how to fix them. - [Informational vs transactional AI queries in Singapore](https://www.geovector.ai/articles/informational-vs-transactional-ai-queries-in-singapore): how query intent changes when AI answers appear. - [How to measure brand presence in AI conversations](https://www.geovector.ai/articles/how-to-measure-brand-presence-in-ai-conversations): the full measurement framework. ## Sources [^fn-1]: [ai.google.dev](https://ai.google.dev/gemini-api/docs/google-search): Gemini API documentation for Grounding with Google Search, describing how the model decides to search, generates and runs queries, and links text segments to source URLs. [^fn-2]: [blogs.bing.com](https://blogs.bing.com/search/may_2023/Bing-at-Microsoft-Build-2023): Microsoft's Yusuf Mehdi announcing Bing as the default search experience in ChatGPT, May 23, 2023. [^fn-3]: [developers.openai.com](https://developers.openai.com/api/docs/bots): OpenAI crawler documentation for OAI-SearchBot, GPTBot and ChatGPT-User, including the robots.txt recommendation and the 24-hour update window. [^fn-4]: [gs.statcounter.com](https://gs.statcounter.com/search-engine-market-share/all/singapore): StatCounter search engine market share in Singapore, September 2026. [^fn-5]: [developers.google.com](https://developers.google.com/search/docs/crawling-indexing/google-common-crawlers): Google's crawler documentation for the Google-Extended token, covering Gemini training, Gemini Apps grounding, and no effect on Google Search. [^fn-6]: [yozigo.ai](https://www.yozigo.ai/blogs/chatgpt-vs-perplexity-vs-gemini-citations-2026): Yozigo study of 232,838 answers for 37 brands across six AI engines, 29 June to 27 September 2026, with cited sources analysed for 18,007 answers from 5 to 20 September; covers domains per answer and own-site and third-party citation shares. [^fn-7]: [arxiv.org](https://arxiv.org/abs/2601.16858): Chen, Wang, Chen and Koudas, "Navigating the Shift: A Comparative Analysis of Web Search and Generative AI Response Generation", 1,000-query comparison of AI citations with Google's top 10, revised May 2026. [^fn-8]: [developers.google.com](https://developers.google.com/search/docs/appearance/ai-features): Google Search Central guidance on AI Overviews and AI Mode, covering eligibility, query fan-out, and no special markup or AI text files. [^fn-9]: [edb.gov.sg](https://www.edb.gov.sg/en/business-insights/insights/big-techs-global-aspirations-take-root-in-asia.html): Singapore Economic Development Board article quoting OpenAI's Oliver Jay on Singapore's per capita ChatGPT usage, May 20, 2026. [^fn-10]: [singrank.com](https://singrank.com/blog/generative-engine-optimization-singapore/): SingRank guide to GEO in Singapore, including a robots.txt check of 219 Singapore service-business websites on 25 September 2026. [^fn-11]: [support.google.com](https://support.google.com/business/answer/3038177): Google's guidelines for representing your business on Google Business Profile. [^fn-12]: [arxiv.org](https://arxiv.org/abs/2311.09735): Aggarwal et al., "GEO: Generative Engine Optimization", KDD 2024, reporting visibility gains of up to 40% in generative engine responses. [^fn-13]: [artificialaiseo.com](https://artificialaiseo.com/gemini-vs-chatgpt-what-brands-should-optimize-for/): Artificial AI SEO comparison of Gemini and ChatGPT, listing [gemini.google.com](https://gemini.google.com) and [chatgpt.com](https://chatgpt.com) as the analytics referral sources, updated September 29, 2026. [^fn-14]: [geovector.ai](https://www.geovector.ai/features): GeoVector features page describing weekly brand share across 6 AI engines, share by engine, and Owned, Earned and Outreach citation views.