Sinthax
Sinthax replaces static forms and surveys with AI agents that interview your audience through natural conversation. Describe your goal in a prompt, share one link, and receive summarised responses with suggested next actions.
What is Sinthax?
Sinthax is a web platform that swaps the static form for a conversation. Instead of laying out fields and branching logic, you describe your objective in one sentence - collect feedback on my new feature, or understand why my customers churn - and the platform builds an AI agent that interviews your audience on your behalf. The agent writes its own questions, reads each answer and asks follow-ups on the spot, which is precisely what a fixed questionnaire cannot do.
Distribution is deliberately plain. Each agent gets one link. You paste it into an email, a website, a social post or a bio, and respondents start talking straight away, creating no account and installing nothing. On the other end every response is summarised automatically, its key points highlighted, and the platform attaches suggested next actions to each insight, so the evening usually spent reading free-text answers largely disappears.
The publisher, Sinthax Inc., documents six use cases on dedicated pages: customer feedback, product research, lead qualification, market research, event management and employee feedback. The argument is the same across all six - forms produce shallow answers and high drop-off, while an adaptive conversation produces better completion and richer material. Several agents can run at once, one per objective.
The conversations themselves are generated by third-party models: OpenAI, Anthropic, Google and Grok are named in both the Terms and the privacy policy. Authentication runs through WorkOS, with SSO on the Enterprise plan, and billing through Stripe. The product is web-only - no mobile app, no browser extension and no public API - while the integrations advertised on the Pro plan remain labelled coming soon, alongside custom subdomains, conversion tracking and drop-off rates.
Pricing runs Free, Pro and Enterprise, with a paid add-on to remove Sinthax branding. The company behind it is thinly documented: no postal address, no about page, no named team, and one email address serving support, legal and data-protection requests alike. The Terms are governed by Delaware law and caution, in their own words, that AI output may be inaccurate and should be verified by a human.
What it does
- Generate a conversational AI agent from a plain-language prompt
- Interview customers, prospects or employees through adaptive chat
- Ask automatic follow-up questions that dig past a first answer
- Summarise every response and surface its key points
- Suggest concrete next actions for each insight collected
- Collect answers through one shareable link, with no respondent account
- Run several agents in parallel, one per objective
When to use Sinthax / When not to
A quick filter to help you decide if Sinthax is the right fit.
When to use Sinthax
- Product teams running discovery and prioritisation without a dedicated user researcher
- Marketing and CX teams collecting customer feedback that goes beyond a rating scale
- Sales and growth teams qualifying inbound leads and capturing buying intent
- HR and people teams gathering candid employee feedback on culture and retention
- Founders and small teams validating an idea quickly, with no coding and no form building
When not to use Sinthax
- Teams needing programmatic access: Sinthax publishes no API, and its integrations are still marked coming soon
- Organisations under GDPR scrutiny: no compliance statement, no DPA and no EU representative are published
- Anyone needing mobile or offline collection: the product is web-only, with no app and no extension
- Research operations requiring statistical analysis, quota management or panel recruitment
- Buyers who need a locatable vendor: no postal address, no team page and no company registry record could be found
How to use Sinthax
A typical end-to-end flow, from setup to results.
- Create an account on the Sinthax platform; authentication runs through WorkOS, with SSO available on the Enterprise plan
- Describe in one sentence what you want to collect, for example understanding why customers churn
- Let Sinthax generate the agent and its opening questions from that prompt
- Review the agent and apply brand customisation if you are on a paid plan
- Copy the unique link the platform gives you
- Share it by email, on your website, across social media or in a bio
- Respondents click and start chatting immediately, with no account to create
- Let the agent adapt its questions and ask follow-ups during each conversation
- Read the automatic summary and the suggested actions for each response in the dashboard
- Create further agents for other objectives, and upgrade if you exceed your monthly response allowance
Pros & Cons
Pros
- Setup takes about thirty seconds: no form to design, no code, no technical skill
- Adaptive follow-ups reach a depth that a fixed questionnaire cannot
- Respondents need no account, which removes the usual drop-off at sign-up
- Analysis is automatic: summaries and suggested actions replace manual sorting
- A permanent free plan lets you test the product without a credit card
- The privacy policy names its subprocessors explicitly, which many vendors avoid
- The Terms state plainly that AI output can be wrong and needs human verification
Cons
- No public API, and the integrations advertised on the Pro plan are still marked coming soon
- Web-only: no mobile app, no browser extension, no offline collection
- The free plan allows five responses in total, not five per month
- A steep gap between free and 99 USD per month, the former 29 USD entry tier having been withdrawn
- No GDPR statement, no DPA, no security certification and no stated retention period
- Conversation content goes to four third-party model providers with no published stance on training
- The publisher is hard to identify: no address, no about page, and one email for support, legal and data rights
Pricing & Plans
Sinthax offers a permanent free plan that requires no credit card and covers five responses in total, with a single user and basic support. The cheapest paid entry point is the Pro plan at 99 USD per month, quoted at its default tier of 500 responses per month and five users. The Pro plan carries a volume slider running from 250 to 5,000 responses per month; the price attached to the 250-response step is computed in the browser and is not published, so a lower entry point may exist. Enterprise pricing is quoted on request. Removing Sinthax branding costs a further 59 USD per month. All fees are quoted and payable in United States dollars, are non-refundable, and exclude applicable taxes.
- 0 USD - 5 responses in total
- 1 user
- basic support
- no credit card required
- 99 USD per month at the default tier of 500 responses per month - 5 users
- brand customisation
- Slack and priority support
- volume slider from 250 to 5
- 000 responses
- custom pricing - tailored response limits and seats
- Single Sign-On
- VIP support and a dedicated outcomes manager
- 59 USD per month - removes Sinthax branding from your agents
Data, GDPR & hosting
A consolidated view of how Sinthax handles your data.
GDPR overview
There is no GDPR implementation to report. The words GDPR and General Data Protection Regulation appear nowhere on the site. The privacy policy acknowledges that, depending on your location, you may hold rights of access, rectification, erasure and restriction, and routes every request to a single support address. Beyond that, nothing: no lawful basis, no Article 27 EU representative, no data protection officer, no DPA offered and no transfer mechanism described. Section 7 simply states that using the Service constitutes consent to your data being transferred to and processed in the United States. A July 2025 version of the same policy did invoke the European Commission's Standard Contractual Clauses and listed portability and objection rights; the current rewrite removed both. For an EU controller this is a documentation gap, not a compliance position.
Who owns the data?
Under section 4.2 of the Terms of Service you retain all ownership rights in your User Content, which covers your conversation prompts, your agent configurations and the answers collected from your respondents. You grant Sinthax Inc. a worldwide, royalty-free licence to use, host, store, reproduce and display that content, expressly limited to what is reasonably necessary to provide, maintain and improve the Service. Sinthax and its licensors keep ownership of the platform itself. Section 2.3 then places responsibility squarely on you: you must hold every right needed to submit and process the content you gather, including the personal data your respondents disclose.
Reuse rights
You may reuse the responses you collect without asking Sinthax for permission. Ownership stays with you, and no clause restricts analysing, publishing or commercially exploiting your own data. The limits sit elsewhere. The Terms forbid using the Service to build a competing product, and they make you responsible for holding the rights required to process what your respondents tell you, which means consent and lawful basis are your obligation rather than the vendor's. Two practical caveats temper this. Sinthax documents no export function, so reuse depends on what the dashboard lets you extract. And conversation content is transmitted to OpenAI, Anthropic, Google and Grok to generate replies and summaries, while the vendor publishes no position on whether that content trains models.
Data retention & training
Hosting summary
Sinthax publishes almost nothing about where it hosts data. The only jurisdiction stated is the United States: section 7 of the privacy policy warns that your information may be transferred outside your own jurisdiction, and that using the Service constitutes consent to processing there. No region, data centre or hosting provider is named in any document, and there is no option to choose a storage location. Technically, the domain resolved on 25 August 2026 to 216.198.79.1, an anycast address on Amazon's AS16509 network fronted by Vercel, which is consistent with United States hosting but is an observation rather than a commitment. On security the vendor claims encryption at rest and in transit and says access to sensitive data is restricted to authorised personnel, without further detail. No SOC 2 report, ISO 27001 certificate or equivalent audit is claimed, and Sinthax acknowledges that no method of transmission or storage is completely secure. Conversation content additionally passes to OpenAI, Anthropic, Google and Grok, whose own hosting arrangements are not described.
Things to keep in mind
Risks and trade-offs to weigh before adopting Sinthax.
- Every conversation you collect is forwarded to OpenAI, Anthropic, Google and Grok, and Sinthax publishes no position on whether that content is used to train models
- No retention period is stated anywhere, so you cannot tell how long respondent answers are kept or when they are deleted
- People disclose more in conversation than in a form; an agent that probes and follows up raises the duty of care you owe your respondents
- Automatic summaries and suggested actions invite you to stop reading the raw answers, and the Terms themselves warn that AI output may be inaccurate
- Five features advertised on the Pro plan are marked coming soon and are not delivered today
- The publisher cannot be located: no postal address, no named team, and no company registry record matching Sinthax Inc. could be found
- The Terms allow immediate suspension or termination without notice, and fees paid are non-refundable
Setup & Integrations
Technical difficulty
Very low. There is nothing to install, no code to write and no form to design. You create an account through WorkOS, type one sentence describing what you want to collect, and the agent is generated; the vendor puts setup at about thirty seconds. Distribution is a single link you paste wherever you like, so there is no embedding or integration work. The corollary is that there is nothing to integrate either: with no API and no webhooks, a developer has no way to connect Sinthax to your existing stack.
Deployment
Supported languages
Behind Sinthax
Resources
All the official URLs gathered for verification and reference.
Alternatives
Tools that compete with or complement Sinthax.
Frequently asked questions
What is Sinthax?
How is Sinthax different from Typeform, Google Forms or SurveyMonkey?
Do I need technical skills to use it?
How long does it take to set up an agent?
Is there a free plan, and what does the paid plan cost?
Does Sinthax offer an API or integrations?
Where is my data processed, and who else sees it?
Does Sinthax comply with the GDPR?
Can I use Sinthax for several projects at once?
Should you pick Sinthax?
Sinthax does one thing and does it neatly: it turns a form into a conversation. Describing an objective in a sentence and receiving a working agent seconds later is genuinely faster than building a questionnaire, and the automatic follow-ups reach material that a fixed form never surfaces. Six documented use cases, summaries with suggested actions, and a link that respondents can use without an account make the product easy to justify for a team that needs qualitative feedback this week.
The reservations are about everything around the product rather than the product itself. There is no API and no integrations, so nothing connects to your existing stack. The tool is web-only. The free plan is a five-response taster rather than a working tier, and the jump to 99 USD per month is abrupt now that the old 29 USD step has gone - and the Pro price itself depends on a volume slider whose lower step is never shown as a number.
The governance gaps deserve more weight. The site does not mention the GDPR once, offers no DPA, names no EU representative, claims no certification, and states no retention period at all - while every conversation is forwarded to four third-party model providers with no published position on training. An earlier version of the privacy policy was more careful, citing EU Standard Contractual Clauses and a minimum age of sixteen; both clauses were removed. The publisher is also hard to pin down: no address, no team, and no company register we could reach has any record of Sinthax Inc.
Worth trying if you want fast qualitative insight and your data is not sensitive. Harder to defend in a regulated setting, or anywhere procurement asks who the vendor actually is.
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