Chatbase vs CustomGPT vs Sider: which AI chatbot builder ships the bot you actually need?

Drafted May 24, 2026 by Pondero Editorial.

These three keep landing in the same "build a chatbot trained on my data" search, and they answer three different questions. Chatbase builds a support agent that lives on your website and resolves tickets. CustomGPT builds a document-grounded answer engine that refuses to make things up. Sider is not a site-bot at all; it is a browser sidebar that assists you on whatever page you are reading. Pick on price alone and you can end up paying for a support deflection tool when what you needed was a research sidebar.

The fast version: ship Chatbase when you want a customer-support agent embedded on your site that takes actions and deflects tickets; ship CustomGPT when accuracy and citations matter more than chat polish, like an internal knowledge base or a docs Q&A that must say "I don't know"; use Sider when the job is helping you across the web, not answering your customers. Below is the reasoning per tool, a feature split, and three buyer profiles. For the wider category, see our AI agent builders directory.

Why "where the bot lives" decides this

The deciding axis is not training quality, it is deployment surface. Chatbase and CustomGPT both ingest your content and answer questions, but Chatbase's output is a customer-facing widget wired into your help desk and CustomGPT's output is a grounded answer API you can put behind internal search or a docs page. Sider lives in your browser, not on your site, and helps the operator rather than the customer. Decide who talks to the bot first. Customers on your website point to Chatbase. Employees querying internal docs, or a docs page that must cite sources, point to CustomGPT. You, reading and researching across tabs, point to Sider.

Three-way feature split

Dimension	Chatbase	CustomGPT	Sider
Built for	Customer-support agents on your site	Document-grounded answers with citations	Personal browser-side AI assistant
Where it lives	Website widget, help desk, voice/telephony	Embed widget or API behind your own UI	Chrome/Edge sidebar on any page
Primary user	Your customers	Your employees or doc readers	You, the operator
Standout feature	AI Actions and ticket deflection	Anti-hallucination, "I don't know," citations	Deep Research Agent across the open web
Answer style	Conversational support replies	Grounded, source-cited answers	Chat plus multi-source research reports
Free tier	Yes, credit-capped	None, paid only	Yes, daily credits
Paid entry point	Low monthly, credit-based	Higher monthly, agent and query capped	Low monthly, varies by source
API access	Yes (Standard+)	Yes	Limited

Pricing as of May 2026 from each vendor's pricing page: Chatbase, CustomGPT. Sider's published pricing varies widely across third-party sources and its own page blocks automated fetches; treat the range as the shape, not the exact number, and confirm on sider.ai/pricing before you subscribe (our Sider review documents the spread).

Chatbase: the support agent that resolves tickets

Chatbase is purpose-built for customer support. You point it at your help docs, site, and files; it builds an agent; you embed the widget. The differentiator over a generic Q&A bot is AI Actions: the agent can do things mid-conversation, like look up an order, create a ticket, or route to a human, rather than just answering from text. Plans scale on message credits and the number of AI Actions per agent: the free tier is 50 message credits a month on one agent, Hobby is $32/month for 500 credits, and Standard is $120/month for 4,000 credits with help-desk, voice, and API access. (Chatbase pricing)

Embedding the widget is a script tag:

<script>
  window.chatbaseConfig = { chatbotId: "<YOUR_CHATBOT_ID>" };
</script>
<script src="https://www.chatbase.co/embed.min.js" defer></script>

Drop that before </body> and the support bubble renders on every page. To send a message through the API instead (for a custom UI or a backend test):

curl -X POST https://www.chatbase.co/api/v1/chat \
  -H "Authorization: Bearer <CHATBASE_API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "chatbotId": "<YOUR_CHATBOT_ID>",
    "messages": [{ "role": "user", "content": "How do I reset my password?" }]
  }'

You get a support-shaped reply grounded in the docs you trained it on. The credit model is the thing to watch: a busy support site burns 4,000 messages fast, so map your monthly ticket volume to a tier before you commit.

Pick Chatbase when the bot faces your customers and the goal is deflecting support volume. Skip it when you need the bot to never guess on a compliance-sensitive answer, or when the consumer is internal staff rather than customers.

CustomGPT: grounded answers that admit what they do not know

CustomGPT optimizes for one thing support bots usually do not: refusing to hallucinate. Its pitch, in the vendor's own words, is to "create your AI that knows when to say 'I don't know'," and the product wraps that with inline citations back to the source documents so a reader can verify the answer. (CustomGPT pricing) That makes it the pick where a wrong answer is expensive: regulated industries, technical docs, internal policy Q&A.

There is no free tier. Standard is $99/month for 10 agents, 1,000 queries a month, and 5,000 documents per agent; Premium is $499/month for 25 agents, 5,000 queries, white-label, and auto-sync. (CustomGPT pricing) The query ceiling, not the document count, is usually the binding limit, so size on expected monthly questions.

Querying an agent over the API returns the answer plus its sources:

curl -X POST "https://app.customgpt.ai/api/v1/projects/<PROJECT_ID>/conversations/<SESSION_ID>/messages" \
  -H "Authorization: Bearer <CUSTOMGPT_API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "What is our refund window for annual plans?"
  }'

The response carries the grounded answer and a citations array pointing at the documents it used. That citations array is the feature: you can render a source label like "policy doc, page 4" next to the answer, which is the difference between a bot a compliance team will sign off on and one they will not.

Pick CustomGPT when accuracy and provenance beat conversational polish, especially for internal knowledge or a docs site. Skip it if you want a free tier to prototype on, or if the job is high-volume customer-support deflection with action-taking, where Chatbase is the better-shaped tool.

Sider is the odd one out, and that is the point of including it: people searching "chatbot trained on my data" sometimes actually want a personal assistant, not a deployable bot. Sider is a browser extension that pins an AI sidebar to every page in Chrome or Edge. Its differentiator is the Deep Research Agent, which runs a multi-step search across the open web and returns a cited report. Our Sider review covers it in depth; the Chrome Web Store listing reports roughly 5,000,000 users and a 4.9 rating across about 112,000 reviews. (Chrome Web Store listing summary, May 2026)

There is no API embed and no widget to ship. The "setup" is the install and a click path:

1. Install the Sider extension from the Chrome Web Store.
2. Pin the sidebar; sign in.
3. Open any page, hit the sidebar, pick a model (GPT, Claude, Gemini, etc.).
4. For research, open the Deep Research Agent and give it a scoped prompt.

The free tier is 30 basic credits per day, which is generous for the category; a basic chat costs one credit and premium-model chats and Deep Research runs cost more. (Tools For Humans Sider review) Sider's published pricing has drifted across third-party reviews enough that the safe move is to open the dashboard yourself; our review documents six different tier structures reported as "current" in the last year.

Pick Sider when the job is helping you read, research, and write across the web. It is not a tool for putting a bot on your own site or behind internal search; for that you are back to Chatbase or CustomGPT.

A scenario that splits the three

Say you run a 12-person SaaS. You have three jobs on the roadmap: cut support ticket volume on the marketing site, give the success team an internal Q&A over 200 pages of policy and runbooks that must cite sources, and give yourself a faster way to research competitors while you browse.

Cut support ticket volume on the site: Chatbase. Embed the widget, train on your docs, turn on AI Actions for order lookups and ticket creation.
Internal policy Q&A that must cite sources and never guess: CustomGPT. The "I don't know" behavior and citations are exactly what a success team needs to trust the answer.
Your own competitor research while browsing: Sider. The Deep Research Agent in the sidebar replaces the tab-juggling.

Three jobs, three tools, because "chatbot trained on my data" was never one product category. Most teams have one dominant job; pick the tool that owns it and ignore the other two until a second job actually shows up.

Which one to ship

If the bot faces your customers and the win is deflecting support volume with an agent that can take actions, ship Chatbase. Map your monthly message volume to a credit tier first; that is the cost that bites.

If a wrong answer is expensive and you need grounded responses with citations and an explicit "I don't know," ship CustomGPT. It is the pick for internal knowledge bases and compliance-sensitive docs Q&A, and the lack of a free tier means you should size the query ceiling before committing to its entry Standard tier (priced on CustomGPT's pricing page).

If you do not actually need a deployable bot and what you want is an AI assistant that rides along while you browse and research, Sider is the tool, and its free tier of 30 daily credits is enough to know within a day whether the sidebar fits your work.

The default for a team shipping a customer-facing bot is Chatbase; the default for a provenance-sensitive internal bot is CustomGPT. Sider only wins when the real job was personal assistance all along. Decide who talks to the bot, and the choice falls out.