Prompto is live · free · last verified 22 Oct 2026 · viability monitor
Prompto
Open-source Angular PWA that runs side-by-side LLM comparisons in your browser with no backend server.
If your question is "which model handles this prompt best," Prompto's Arena mode answers it without glue code, and browser-local storage means nothing goes to a vendor server. It is a solo tool at v1.0.0: no team sharing, no cross-device sync, and you configure your own LangChain connection before it will answer anything. Choose Prompto for fast, private prompt and model testing on one machine; look at LibreChat or TypingMind when you need a shared, multi-user workspace.
Verdict generatedVerified 8d ago · liveness 53/100 · cite: rightaichoice.com/tools/prompto
- Developers comparing output quality across multiple LLMs on the same prompt
- Researchers running prompt A/B tests who need reproducible side-by-side results
- Privacy-conscious users who want prompts handled in-browser rather than on a vendor server
- Tinkerers evaluating whether a cheaper LangChain-supported model holds up on a task
- Teams that need shared prompt libraries or multi-user workspaces
- Anyone expecting a hosted service with a pre-configured LLM out of the box
- Production chat deployments that need audit trails, retrieval, or plugins
We scan live Reddit threads, YouTube comments, X posts, G2 reviews and other communities — and hand you an honest verdict in under a minute.
- Honest verdict, not marketing
- Real pros & cons from real users
- Attributed quotes with receipts
3 free scans · no card needed
Skip Prompto if you need a shared, multi-user prompt library or cross-device sync, since everything it stores lives in one browser profile's local storage.
Prompto itself is MIT-licensed open source, but you pay your LLM provider directly for every prompt — Arena and Discussion modes multiply that cost because they fire the same input at several models at once.
Prompto is a free, MIT-licensed app, so the real cost comparison is against your LLM provider bill rather than a subscription. It undercuts hosted chat interfaces such as TypingMind or LibreChat's paid hosting by removing the software fee entirely, and its Arena and Discussion modes can save money indirectly by showing you that a cheaper LangChain-supported model is good enough before you standardize on an expensive one.
In short
Prompto — Open-source Angular PWA that runs side-by-side LLM comparisons in your browser with no backend server. Best for Developers comparing output quality across multiple LLMs on the same prompt, Researchers running prompt A/B tests who need reproducible side-by-side results, Privacy-conscious users who want prompts handled in-browser rather than on a vendor server. Free to use.
What is Prompto?
Prompto — Open-source Angular PWA that runs side-by-side LLM comparisons in your browser with no backend server. Best for Developers comparing output quality across multiple LLMs on the same prompt, Researchers running prompt A/B tests who need reproducible side-by-side results, Privacy-conscious users who want prompts handled in-browser rather than on a vendor server. Free to use.
Prompto is an open-source Angular Progressive Web App — v1.0.0, MIT-licensed — that puts several language models behind one browser tab. It talks to providers through LangChain.js directly from the client, so there is no backend server between your prompts and the model. The interface splits work into five modes: Chat (keeps conversation context), Notebook (sends a prompt with no prior context for isolated answers), Templates (build and reuse prompts with dynamic contextual elements), Arena (lines up responses from multiple LLMs on the same prompt for direct comparison) and Discussion (runs a conversation between multiple AI personas). Temperature is adjustable from the dashboard, and a dark mode toggle is in the sidebar. Everything — settings, chat histories, templates, configurations — lives in browser local storage, and the settings page has a control to clear all stored data. Prompto ships no model of its own: you connect a LangChain-compatible LLM before anything answers, and the app shows a connection error until you do. The scrape shows a configured Ollama llama4 connection at temperature 0.7. It is aimed at developers, researchers and tinkerers who want to A/B the same prompt across models without writing glue code or paying middleware, and at privacy-minded users who would rather not route prompts through a vendor server.
Key features
- Arena mode lines up responses from multiple LLMs side by side
- Chat mode maintains conversation context across turns
- Notebook mode sends prompts with no prior context for isolated answers
- Templates for building and reusing prompts with dynamic contextual elements
- Discussion mode runs conversations between multiple AI personas
- Switch between LLMs supported by LangChain.js from one view
- Dashboard temperature control (scrape shows 0.7)
- Runs entirely in-browser as an Angular Progressive Web App
- No backend server — browser talks straight to the LLM provider
- Settings, chat histories and templates saved in browser local storage
- Clear-all-stored-data control on the settings page
- Dark mode toggle in the sidebar
- Collapsible sidebar navigation across Dashboard, Chat, Notebook, Templates, Arena and Discussion
- MIT-licensed open-source codebase on GitHub at v1.0.0
- No account or installation required — works in the browser
Behind the verdict
Prompto's sharpest idea is the split between Chat and Notebook. Chat carries conversation context forward, Notebook deliberately sends a prompt with none — which is exactly what you want when you are testing whether a model actually nails the task or is riding on prior turns in the thread. Pair that with Arena, which lines up responses from multiple LLMs to the same prompt, and Discussion, which runs a multi-persona conversation, and you get four or five distinct testing postures in one sidebar instead of one chat box trying to be everything. Underneath, the architecture is the selling point. It is an Angular PWA talking to LangChain.js-supported LLMs straight from the browser, so there is no server in the middle and no vendor account gating the app. Settings, histories and templates live in local storage, and there is a control to wipe all of it from the settings page. Temperature sits on the dashboard, so you can move a run from predictable to exploratory without digging through menus. The honest caveats are structural, not cosmetic. Prompto ships no model — the scrape shows a connection error state until you wire up a LangChain-compatible provider, and the one visible configuration is Ollama running llama4 at temperature 0.7. You bring keys and you absorb usage costs. Because local storage is the source of truth, everything is scoped to that browser profile on that machine: no shared prompt library, no multi-user workspaces, no audit trail, no cross-device sync. Prompto's own copy notes local storage can be exposed to others in some situations, which is why the clear-data control matters. And nothing here replaces a production chat platform — there is no retrieval, no plugin ecosystem, no user management. Where it fits: individual developers evaluating whether a cheaper LangChain-supported model holds up on a specific task, researchers who want reproducible side-by-side results on a frozen prompt, and privacy-conscious tinkerers who would rather self-host or run entirely in-browser than hand prompts to a vendor. Where it does not: any team that needs a shared prompt library, any deployment that needs audit trails or retrieval, and anyone who expects a hosted service with a pre-configured model out of the box.
Models under the hood
as of 2026-09-09
Limitations
- Prompto is a v1.0.0 project with limited documentation, and support is community-driven through GitHub.
- It ships no model of its own: the app shows a connection error until you configure a LangChain-compatible LLM, so you supply your own provider credentials and absorb the usage costs.
- Because everything lives in browser local storage, data is scoped to that browser profile on that machine — there is no cross-device sync, no shared workspace, and Prompto's own copy notes local storage can be exposed to others in some situations (the settings page has a wipe control for that reason).
- The web interface needs a modern browser and a stable internet connection to reach your provider.
- No collaboration or sharing features exist.
as of 2026-10-09
Researching Prompto? Get your full AI stack in 60 seconds.
Free, no signup — tell us your goal and get tools matched to your budget & existing stack.
Is Prompto still active?
Prompto is live · free · last verified 22 Oct 2026 · viability monitor.
Viability score
How well maintained and how widely used is Prompto? Built from what the vendor actually publishes (docs, changelog, tutorials, integrations, pricing), whether the site is live, and how much real users discuss it. How we calculate this
Last calculated: October 2026
How we score →What do users say about Prompto?
What people actually say about Prompto — is it worth it?
We scanned public community sources for Prompto on Oct 23, 2026 and could not establish that the discussion we found is about this tool rather than something else sharing its name. Only 1 of the posts we fetched could be positively tied to Prompto. Rather than publish a sentiment score built on the wrong subject, we publish nothing here and re-run the scan.
How we verified this
Every listed fact about Prompto— pricing, features, links, status — is re-read from the vendor's own pages by our verification pipeline and each change is logged with a date; the last pass ran on 22 Oct 2026. Pages mix model-assisted synthesis with human review; see how we verify.
Verification history
We have re-verified Prompto 13 times since . Each pass re-reads the vendor's own pages and re-checks every listed field against that evidence; passes where nothing had changed are marked as such.
- — changed SSL certificate
- — changed link health
- — changed use cases, hidden costs, description, integrations, limitations, switching in, switching out, models, pricing fit, our verdict, setup time, who it suits, who should skip it, summary, features
- — changed pricing tiers, summary, our verdict, who should skip it, description, who it suits, features
- — changed setup time, who it suits, description, our verdict, hidden costs, limitations, switching in, switching out, who should skip it, pricing fit, summary
- — changed domain expiry, SSL certificate
Showing the 6 most recent of 13 verification passes.
Free to cite with attribution — this page re-verifies continuously.
How much does Prompto cost in 2026?
Prompto: Free to use. Pricing last verified 22 Oct 2026.
Plans compared
Every published Prompto tier, its price as the vendor publishes it, who it fits, and what it adds over the tier below. The 12-month cost projection follows.
| Plan | Price | Billing | Who it's for |
|---|---|---|---|
| Free | Free | — | Developers, researchers and tinkerers testing prompts across several models on their own machine, with their own LLM provider credentials.Adds: Starting tier — the only tier. MIT-licensed, runs in the browser as a PWA with no account, and all five modes (Chat, Notebook, Templates, Arena, Discussion) are included. |
12-month cost
Project the real annual outlay, including the implied monthly cost when only an annual tier is published.
Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
Where the pricing makes sense
The company stage and team size where Prompto's pricing actually pencils out — and where peers do it cheaper.
Prompto is a free, MIT-licensed app, so the real cost comparison is against your LLM provider bill rather than a subscription. It undercuts hosted chat interfaces such as TypingMind or LibreChat's paid hosting by removing the software fee entirely, and its Arena and Discussion modes can save money indirectly by showing you that a cheaper LangChain-supported model is good enough before you standardize on an expensive one.
Has Prompto's pricing changed?
No plan price for Prompto has moved since we began logging in Aug 2026; the pricing page is re-read on every verification pass.
Who should pick Prompto?
Pick Prompto if you are Developers comparing output quality across multiple LLMs on the same prompt, Researchers running prompt A/B tests who need reproducible side-by-side results, Privacy-conscious users who want prompts handled in-browser rather than on a vendor server, Tinkerers evaluating whether a cheaper LangChain-supported model holds up on a task.
Look elsewhere if you are Teams that need shared prompt libraries or multi-user workspaces, Anyone expecting a hosted service with a pre-configured LLM out of the box, Production chat deployments that need audit trails, retrieval, or plugins, Users who rely on cross-device sync and don't want browser-local storage as the source of truth.
Skip it if Skip Prompto if you need a shared, multi-user prompt library or cross-device sync, since everything it stores lives in one browser profile's local storage.
GeneratedReal-world workflow fit
Concrete scenarios for the personas Prompto actually fits — and what changes day-one when you adopt it.
Connects a LangChain-compatible provider, writes the production prompt once, then runs it in Arena against two or three candidate models at temperature 0.7 to compare tone and correctness side by side.
Outcome: A defensible model choice backed by side-by-side output on the actual prompt, with no glue code written and no server stood up.
Drafts the prompt in Templates with dynamic contextual elements, tests it in Notebook to see the no-context baseline, then re-tests in Chat to see whether conversation history changes the answer.
Outcome: A reusable template that is known to work both with and without prior context, saved in local storage for the next project.
Self-hosts the Angular build or opens it in-browser, points it at a local Ollama instance running llama4, and runs multi-persona Discussion threads on sensitive material.
Outcome: Prompt testing happens without a vendor server in the path, and the researcher can wipe every stored setting and history from the settings page when done.
Use cases
- Compare responses from several LLMs side by side on the same prompt before standardizing on one
- Round-trip the same prompt through Notebook to see how a model does without conversation context helping it
- Adjust temperature from the dashboard to test how far a prompt's output moves between runs
- Build reusable prompt templates with dynamic contextual elements for recurring tasks
- Run multi-persona Discussion threads to stress-test an idea from several angles at once
- Self-host the interface so prompts never pass through a vendor server
- Fork or contribute to the Angular codebase under the MIT License
Setup time & first value
How long it actually takes to get something useful out of Prompto — broken out by persona, not the marketing-page minute.
Developers already holding a provider key: a couple of minutes — open the app, connect a LangChain-compatible LLM, and Arena is usable. Local-model users running Ollama: add the time to pull the model weights first, which usually dwarfs the app setup. Self-hosters cloning the Angular repo should budget build-and-deploy time on top.
Switching to or from Prompto
How to bring data in from common predecessors and how to get it back out — written for the switcher, not the buyer.
- →From juggling provider chat tabs: point Prompto at the same LangChain-compatible providers and run the prompt once in Arena instead of pasting it into each tab.
- →From ad-hoc scripts around an LLM SDK: move the prompt into Templates with dynamic contextual elements and use Notebook for the isolated baseline you were scripting by hand.
- →From a local Ollama chat UI: keep the same Ollama endpoint and pick up Arena and Discussion modes on top of it.
- ↗To LibreChat or TypingMind: move to a hosted workspace when you need shared prompt libraries, multi-user accounts, or cross-device sync instead of browser local storage.
- ↗To a production chat platform: export what you need from your own prompt templates by hand, since Prompto has no audit trail, retrieval, or plugin layer to carry over.
Integrations
Tutorials & Learning
YouTube returned 6 videos for “Prompto”, and we withheld 6: 6 could not be judged, because “Prompto” is a single word that other videos use for other things. We are showing none, because we could not prove any of them are about Prompto.
Official links
What are the best Prompto alternatives?
The closest alternatives to Prompto we list are LibreChat, Cherry Studio and Anse. Ranked by direct product-type match, not category overlap.
| Alternative | Pricing | Starts at | Last verified |
|---|---|---|---|
| LibreChat | Free | Free | — |
| Cherry Studio | Freemium | Pricing not published | — |
| Anse | Free | Free | — |
Alternatives to Prompto
View all
LibreChat
Self-hosted multi-model AI chat for teams that keep prompts, agents, and MCP tools on their own infrastructure.
Cherry Studio
Cherry Studio is a free, open-source desktop AI workbench that runs models from 50+ cloud providers and local deployments in one window
Tools that pair well with Prompto
Common stack mates teams adopt alongside Prompto, with the specific reason each pairing earns its keep.
LibreChat
Self-hosted multi-model AI chat for teams that keep prompts, agents, and MCP tools on their own infrastructure.
Cherry Studio
Cherry Studio is a free, open-source desktop AI workbench that runs models from 50+ cloud providers and local deployments in one window
Anse
Anse is a free, open-source desktop chat client that runs your own OpenAI, Azure OpenAI, Google and Replicate API keys from one window.
Prompto vs its closest rival
Prompto's closest head-to-head is with Surge Ai — If you're a solo developer or researcher experimenting with multiple LLMs and need a free, open-source interface, Prompto is your tool. But if you're building production AI and require expert human feedback for RLHF, red teaming, or complex benchmarks, Surge AI is essential — recent partnerships with Microsoft and novel benchmarks like Antidote and Riemann-bench show its unique value for frontier AI alignment. Verdict generated
Head-to-head comparisons
Prompto vs Surge Ai
If you're a solo developer or researcher experimenting with multiple LLMs and need a free, open-source interface, Prompto is your tool. But if you're building production AI and require expert human feedback for RLHF, red teaming, or complex benchmarks, Surge AI is essential — recent partnerships with Microsoft and novel benchmarks like Antidote and Riemann-bench show its unique value for frontier AI alignment.
GeneratedPrompto vs Praktika
If you're a developer or researcher juggling multiple LLMs for experimentation, Prompto's free, open-source, and self-hostable interface is ideal. If you're a language learner aiming to improve speaking fluency through AI tutors, Praktika's gamified mobile app with personalized feedback is a better choice. They serve entirely different needs—choose based on your primary goal.
GeneratedFrequently asked questions
Used Prompto? Help shape our editorial sentiment research.