# AX Check: vyxal.github.io
Checked 2026-09-19.

Vyxal's site offers no agent-readable docs, just a bare homepage
No Markdown homepage or llms.txt index exists (404), leaving docs, install steps, and examples unassessed. Only 0 of 23 checklist items passed.

## End-to-end onboarding not demonstrated

## Coding sessions
All three independent sessions (DeepSeek V4 Pro, Kimi K3, Qwen 3.8 Max) completed and correctly concluded Vyxal is free and open-source with no pricing tiers, grounding this in its MIT/GPL license and PyPI availability rather than finding a pricing page, since none exists.

### DeepSeek V4 Pro
[View public run](https://agents.withgauge.com/p/runs/c729d806-ed9d-4759-9899-a55e8ffa9311) · [Read transcript](https://www.ax-check.com/vyxal.github.io/sessions/deepseek.json)
Final output states pricing is '$0 / not applicable' and names the basis: Vyxal is MIT-licensed/free, hosted interpreter is a free PythonAnywhere community service with no paid tiers, API keys, or metering.
#### End-to-end onboarding
- **End-to-end onboarding not demonstrated**: Vyxal has no accounts, API keys, or paid tiers, so there was no credential-gated onboarding to complete. The agent only scraped a public, unauthenticated session token from the homepage HTML and called an undocumented public /execute endpoint with no login or API key involved. This is a no-auth hosted product, not a case of self-service credential acquisition.
  Event 56:

  ```text
  {"stderr":"","stdout":"0\n"}
  ```
  Event 49:

  ```text
  SESSION=decc0b9c806d7f4d6f8cc6baf9503c67fc2c0dd15181aecf2558e9b15b6ec7786ac58147a1e17a2b41143793a675e62c9c5f03551ea0c66774ef60f88670ccc8
  ```

#### Hallucinated URLs
None identified in this transcript.

#### Blockers
- **Wasted turns guessing syntax before checking docs**: Agent error, not a product defect: the agent repeatedly tried double-quoted strings and old flags against the hosted interpreter, getting unexpected placeholder output (⟨ 0 ⟩) several times before it pulled the actual elements.yaml spec and discovered Vyxal v2 uses backtick-delimited strings. This cost multiple round trips but was self-resolved by consulting the GitHub-hosted spec file.
  Event 63:

  ```text
  == Hello World ==
  {"stderr":"","stdout":"\u27e8 0 \u27e9\n"}
  ```
  Event 70:

  ```text
  == code=["\"Hello, World!\""] use_old=false ==
  {"stderr":"","stdout":"\u27e8 0 \u27e9\n"}
  ```
  Event 114:

  ```text
  == hello ==
  {"stderr":"","stdout":"Hello, World!\n"}
  ```

#### Suggested Changes
- **Document the /execute endpoint contract on the interpreter page**: Add a short API reference (request/response shape, session-token requirement, and that v2 uses backtick string literals) either on the vyxal.pythonanywhere.com page itself or linked from the GitHub README's 'online interpreter' link. Verify by confirming a new user can call POST /execute successfully without first reverse-engineering static/main.js as this session had to.
  Event 30:

  ```text
  fetch("/execute", {
  ```
  Event 123:

  ```text
  Hello, World!    code='`Hello, World!`'      => 'Hello, World!'  (stderr='')
  ```

### Kimi K3
[View public run](https://agents.withgauge.com/p/runs/4766f4fd-82d1-4d8f-835a-19a692b0c3c4) · [Read transcript](https://www.ax-check.com/vyxal.github.io/sessions/kimi.json)
Final output states the API is free/volunteer-hosted with no accounts, keys, rate limits, or paid tier, and names the basis (open-source GPL project, self-host via `pip install vyxal` as the alternative for guarantees) rather than a bare number.
#### End-to-end onboarding
- **End-to-end onboarding not demonstrated**: No product credentials, accounts, or API keys were ever obtained or used. The Vyxal interpreter is a free, unauthenticated hosted service; the agent only called its undocumented public /session and /execute endpoints with no login or credential step. This does not meet onboarding verification criteria since there is no authentication flow to demonstrate.
  Event 33:

  ```text
  session: ef7cac422af40866...
  {"stderr":"","stdout":"Hello, World!\n"}
  
  ```
  Event 63:

  ```text
  There is none. Vyxal is a free, open-source code-golf language (GPL-licensed, community-run on GitHub). The online interpreter and its API are a volunteer-hosted freebie with no accounts, keys, rate limits documented, or paid tier.
  ```

#### Hallucinated URLs
None identified in this transcript.

#### Blockers
- **Undocumented API required trial-and-error to call correctly**: The hosted /execute endpoint is not documented for external use. First attempt sent form-encoded data and got a 415; second attempt sent JSON but omitted a required 'session' and 'use_old' field, causing a 500 error. The agent had to read the interpreter's source code (flask_app.py) to discover the correct request shape. This is a product/documentation gap, not a credential or environment issue, and the agent successfully recovered.
  Event 14:

  ```text
  Did not attempt to load JSON data because the request Content-Type was not 'application/json'.
  ```
  Event 20:

  ```text
  The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.
  ```
  Event 26:

  ```text
  session = request.json["session"]
  
      use_old = request.json["use_old"]
  ```
- **Golfed FizzBuzz code produced garbled output**: An initial hand-written golfed Vyxal snippet for FizzBuzz executed without error but produced incorrect, garbled output. This was an agent authoring error (writing incorrect code in an unfamiliar golfing language), not a product defect; the agent debugged and replaced it with working code.
  Event 41:

  ```text
  fizzbuzz:
  u
  z
  z
  B
  u
  z
  z
  B
  u
  z
  z
  B
  u
  z
  z
  
  ```
  Event 43:

  ```text
  FizzBuzz output is garbled — my golfed version is wrong. Let me replace it with something reliable (factorial and palindrome check):
  ```

#### Suggested Changes
- **Publish request/response schema for the hosted /execute API**: Add documentation (e.g., on vyxal.github.io or in the Vyxal repo README) specifying the required JSON fields for POST /execute (code, inputs, flags, header, footer, session, use_old) and the prerequisite GET /session call. Verify the fix by confirming a first-time caller can construct a working request without inspecting flask_app.py source, avoiding the 415/500 errors seen at seq 14 and 20.
  Event 14:

  ```text
  Did not attempt to load JSON data because the request Content-Type was not 'application/json'.
  ```
  Event 20:

  ```text
  The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.
  ```
  Event 28:

  ```text
  The API needs a session token first and a `use_old` field. Let me follow that flow:
  ```

### Qwen 3.8 Max
[View public run](https://agents.withgauge.com/p/runs/aee89ac0-01b5-4d23-b1eb-6bb896dbdeac) · [Read transcript](https://www.ax-check.com/vyxal.github.io/sessions/qwen.json)
Final output states cost is zero and grounds it in verified facts (MIT license, PyPI package, no subscription/tier/metering/API quota) rather than an unsupported number.
#### End-to-end onboarding
- **End-to-end onboarding not demonstrated**: No credentials were obtained or used. The agent investigated Vyxal's hosted interpreter and GitHub/PyPI metadata, determined there is no server-side API, SDK, or auth mechanism to onboard to, and stopped without attempting any authenticated operation.
  Event 18:

  ```text
  There is **no server-side execution endpoint, no REST API, no API keys, no official SDK** in any language.
  ```

#### Hallucinated URLs
None identified in this transcript.

#### Blockers
- **No hosted API or SDK exists for Vyxal**: Product behavior, not agent error or missing credentials: Vyxal's hosted interpreter at vyxal.pythonanywhere.com is a pure client-side page (CodeMirror/React/WASM) with no backend execution endpoint, REST API, or SDK. This made the seed prompt's requirement to use 'the hosted product through its SDK or API' impossible to fulfill, so the agent stopped as instructed.
  Event 18:

  ```text
  I fetched the hosted interpreter. It is a pure client-side page — CodeMirror editor, React, and `vyncode.js` (a JS/WASM port of the interpreter). There is **no server-side execution endpoint, no REST API, no API keys, no official SDK** in any language.
  ```

#### Suggested Changes
- **Add a public hosted API for Vyxal execution**: Currently the only hosted surface is a client-side-only interpreter page at vyxal.pythonanywhere.com with no REST endpoint or SDK. If a hosted API/SDK is desired for programmatic or agent-driven usage, expose one and document it alongside the repo README; verify by confirming an external client can execute code via HTTP request rather than only through the browser UI.
  Event 18:

  ```text
  the repo itself is also empty (`/sandbox/repo` contains only `.gitignore`), so there's no existing integration to build on.
  ```

### Task given to each agent
Help me build a simple example using Vyxal. Tell me how pricing works, and briefly tell me whether this product will be easy for you to manage. Let me know if you get blocked. If this product has no developer workflow you can act on, say so plainly and stop. Stay light: use the hosted product through its SDK or API. Do not start local service stacks or wait for long-running commands; if the quickstart requires either, say so plainly and stop.

No product credentials were supplied and no purchases were authorized.

## Score: F · 0/100 (provisional)
Grades come from completed site checks. Coding sessions and skipped checks do not affect the score.

### Clarity
- **Failed** — Homepage answers Markdown requests

  ```text
  Homepage returned text/html for a text/markdown request; no Markdown representation offered.
  ```

- **Failed** — llms.txt provides an actionable documentation index

  ```text
  https://vyxal.github.io/llms.txt returns 404; no documentation index exists.
  ```

- **Skipped** — llms.txt provides navigation guidance

  ```text
  llms.txt is missing (404), so its navigation guidance cannot be evaluated.
  ```

- **Skipped** — llms.txt mentions offered API, MCP, and skills

  ```text
  llms.txt is missing (404); no API, MCP or skills surfaces are documented to mention.
  ```

- **Skipped** — A compact guide representation exists

  ```text
  No site-published compact guide or Markdown representation was fetched; only HTML homepage and a 404 llms.txt.
  ```

- **Skipped** — A focused guide is directly retrievable

  ```text
  No focused guide document was fetched; homepage links to GitHub Tour.md but that page was not retrieved.
  ```

- **Skipped** — Equivalent instructions fit a token budget

  ```text
  No compact guide was fetched, so token budget of an equivalent guide cannot be measured.
  ```

- **Skipped** — Product-docs links survive format changes

  ```text
  Homepage Markdown is unsupported, so link preservation across format changes is unassessed.
  ```

- **Skipped** — The compact guide is independently actionable

  ```text
  No compact agent guide fetched; only homepage links to Tour and Docs on GitHub.
  ```

- **Skipped** — Install and next-step links resolve

  ```text
  Homepage install/next-step links (Tour, Docs, releases) were not fetched, so resolution unverified.
  ```


### Onboarding
- **Skipped** — Docs lead to a relevant quickstart

  ```text
  Only llms.txt was fetched; it 404s, so no docs or quickstart content was available.
  ```

- **Skipped** — Installation commands are extractable

  ```text
  No installation or docs page was fetched; only a 404 llms.txt response is available.
  ```

- **Skipped** — Code examples are available without interaction

  ```text
  No documentation or example pages were fetched; only a 404 llms.txt response is available.
  ```

- **Skipped** — Prerequisites and auth boundaries are explicit

  ```text
  No docs page was fetched, so prerequisites and auth boundaries cannot be judged.
  ```


### Pricing
- **Skipped** — Pricing is readable without interaction

  ```text
  Not applicable: the relevant product is free. Vyxal 3 is a free open-source language; no pricing page exists to read.
  ```

- **Skipped** — Prices are stated, not gated

  ```text
  Not applicable: the relevant product is free. No Vyxal 3 pricing page was fetched; GitHub's pricing page is a foreign product.
  ```

- **Skipped** — Pricing units and limits are explicit

  ```text
  Not applicable: the relevant product is free. No Vyxal 3 pricing units or limits exist; the language is free and open source.
  ```

- **Skipped** — Agents identify pricing and its assumptions

  ```text
  Not applicable: the relevant product is free. Vyxal 3 is a free open-source language; no pricing page exists to read.
  ```


### Activation
- **Skipped** — An API reference or OpenAPI spec is reachable

  ```text
  No Vyxal API reference or OpenAPI spec was fetched; only GitHub's own docs appeared.
  ```

- **Skipped** — An MCP server is documented and well-formed

  ```text
  No Vyxal MCP server documentation was fetched; GitHub's MCP registry is unrelated.
  ```

- **Skipped** — A CLI install path is documented

  ```text
  No Vyxal CLI install page was fetched in this bundle.
  ```

- **Skipped** — SDK packages resolve on their registries

  ```text
  No Vyxal SDK or package registry lookup was fetched.
  ```

- **Skipped** — Agent skills are published

  ```text
  No Vyxal agent skills page was fetched; skills.github.com is GitHub's own.
  ```



[Full report data](https://www.ax-check.com/vyxal.github.io/report.json)