Langtail
Verified Oct 16, 2026 ActiveSpreadsheet-style workbench for writing, testing and shipping prompts, with a firewall on the outputs
Listed on EffectHub ·
Pricing
- Pricing model
- Freemium
- Paid options from
- $99/mo
- Billing
- Monthly
Free tier at zero, Pro at 99 dollars a month and Team at 499, all quoted plus VAT; Enterprise is negotiated. The home page shows no figures at all — they are only on the plan page.
Use tool ↗About Langtail
Langtail treats a prompt as something that has to be tested before it ships. Prompts live in a spreadsheet-like table that non-developers can edit, test suites run them against saved cases, and the same prompt can be replayed across models and parameter settings so the results can be compared side by side. A separate firewall layer screens for prompt injection and unsafe output at runtime. There is a typed TypeScript SDK and an OpenAPI spec, connectors for OpenAI, Anthropic, Google, Meta and Mistral, and a self-hosted option for teams that cannot send prompts out. The vendor is LANGTAIL.COM s.r.o., registered in Prague. The address this product was harvested under now redirects here.
- Platforms
- Web · API
- API
- Yes
- Last verified
- Oct 16, 2026
Verified sources
- Prompt table, testing, cross-model replay, AI Firewall, TypeScript SDK and OpenAPI, and self-hostinglangtail.com ↗
- Free, Pro at 99 and Team at 499 dollars a month plus VAT, with custom Enterpriselangtail.com ↗
- Privacy policy names LANGTAIL.COM s.r.o. with its Czech company ID and registered seat in Praguelangtail.com ↗
- The harvested address returns a 301 to the current domainlangtale.ai ↗
Is Langtail legit?
We don’t label tools safe or unsafe. Below are the records we checked ourselves, each with the date we read it.
- Domain registered
- May 25, 2023 (3 years ago)Registry record (RDAP), registrar Gransy, s.r.o., looked up Sep 6, 2026
- TLS certificate
- Issued by Google Trust Services, valid until Jan 7, 2027Seen in our own connection to the site on Oct 16, 2026
- Last checked
- Oct 16, 2026The site answered
- Operated by
- LANGTAIL.COM s.r.o., CzechiaOur research, card verified Aug 23, 2026
Pros & cons of Langtail
The useful idea is treating prompts like code that needs a test suite, and then handing the editing surface to people who do not write code. Cross-model replay makes swapping providers a measurable decision rather than a leap, and the firewall covers a risk most prompt tools ignore entirely. The step from free to 99 dollars a month is abrupt for a solo developer, and a Czech company of this size is a smaller bet than the observability platforms it competes with.
Pros
- Spreadsheet-style prompt editing that non-developers can actually use
- Test suites and validation runs against saved cases before deployment
- Replay across models and parameter settings for direct comparison
- AI Firewall screens for prompt injection and unsafe output
- Typed TypeScript SDK plus OpenAPI, and a self-hosting option
Cons
- Only one intermediate tier: free, then 99, then 499 dollars a month plus VAT
- No pricing anywhere on the marketing pages, only on the plan page
- Small vendor, and the company gives its details only inside the privacy policy
- Prices are quoted excluding VAT, so the EU figure is higher than the sticker
Best for
- Teams where product or support staff own prompt wording, not just engineers
- Anyone comparing the same prompt across providers before committing
- Deployments that need prompt-injection screening at runtime
Not for
- Solo developers, for whom the jump from free to 99 dollars a month is hard to justify
- Teams already running a full LLM observability stack that covers prompts
Watch out: The harvested address for this product is an old domain that now redirects; bookmark the current one so links do not break later.
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