# Liquid d1 vs pplx-decider

> pplx-decider scores 62.9 (B) to Liquid d1's 43.5 (E) for decision models. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/liquid-d1-vs-pplx-decider
- Markdown: https://www.anchorterminal.com/compare/liquid-d1-vs-pplx-decider.md (~2,400 tokens)
- Slim: https://www.anchorterminal.com/compare/liquid-d1-vs-pplx-decider.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/liquid-d1-vs-pplx-decider.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

pplx-decider scores 62.9 (B) on agent readiness against Liquid d1's 43.5 (E), and leads in 5 of 7 scored categories. Both do decision models.

- Liquid d1: grade E, 43.5/100, rank #883 of 950. Markdown https://www.anchorterminal.com/tools/liquid-d1.md · JSON https://www.anchorterminal.com/api/v1/tools/liquid-d1.json
- pplx-decider: grade B, 62.9/100, rank #417 of 950. Markdown https://www.anchorterminal.com/tools/pplx-decider.md · JSON https://www.anchorterminal.com/api/v1/tools/pplx-decider.json
- Best decision models for AI agents: https://www.anchorterminal.com/best/decision-models/index.md
- All 66 decisions comparisons: https://www.anchorterminal.com/compare/decision-models/index.md

## Which one, for what

### Liquid d1 (E)

Good for: Classification, routing, yes or no gates and rubric scoring over text and images at a low per-token price, or on your own hardware with d1-3B where data can't leave.

Watch for: The terms of 30 September 2026 allow Liquid to train on API content, with no opt-out or zero-retention option found

### pplx-decider (B)

Good for: High-volume classification, routing and rubric scoring over text and images where a team wants a low hosted price and the option to run the same weights itself.

Ahead on:
- Reliability, 61 against 21
- Schema & documentation, 90 against 59
- Agent ergonomics, 76 against 63
- Security & auth, 61 against 35

Watch for: The Decisions API was released in October 2026, so its incident record is days long, and Perplexity's FAQ says it gives no uptime guarantee


## Score by category

| Category | Weight | Liquid d1 | pplx-decider | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 21 | 61 | pplx-decider +40 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 59 | 90 | pplx-decider +31 |
| Agent ergonomics | 13% (16.2 this run) | 63 | 76 | pplx-decider +13 |
| Security & auth | 14% (17.5 this run) | 35 | 61 | pplx-decider +26 |
| Payments & pricing | 10% (12.5 this run) | 27 | 25 | Liquid d1 +2 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 62 | pplx-decider +2 |
| Transparency & trust | 7% (8.8 this run) | 54 | 52 | Liquid d1 +2 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **43.5 · E** | **62.9 · B** | |

## Facts side by side

| Fact | Liquid d1 | pplx-decider |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Liquid AI | Perplexity |
| Hosted endpoint | `https://api.liquid.ai/decisions/v1/systemone` | `https://api.perplexity.ai/v1/decisions` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Pay per use |
| Price for decision models | not published | free |
| x402 | no | no |
| Licence | The hosted d1 model is proprietary under Liquid AI's terms of service. The d1-3B and d1-omni-600M weights and model code are under the LFM Open Licence v1.0, which is based on Apache-2.0 and conditions commercial use on annual revenue under $10 million. Training code and data aren't published | Apache-2.0 for the published weights. The hosted Decisions API is a proprietary service |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-07 | 2026-10-05 |
| Terms last updated | 2026-09-30 | couldn't be read |
| Privacy policy last updated | 2026-09-30 | couldn't be read |
| Customer content may train models | yes | couldn't be read |
| Terms restrict automated access | not found in the text | couldn't be read |
| Terms restrict benchmarking | not found in the text | couldn't be read |
| Terms or service can change without notice | not found in the text | couldn't be read |
| Arbitration or class-action waiver | not found in the text | couldn't be read |

## Verdicts

**Liquid d1.** The hosted API costs $0.04 per million input tokens and takes TypeSafe's System One request, and the d1-3B weights run locally through Transformers or llama.cpp. Liquid's terms allow it to train on API content, and no status page, rate limits or error reference were found. The family launched between 22 September and 7 October 2026.

**pplx-decider.** The hosted Decisions API has an OpenAPI description, typed questions, documented limits and a published price of $0.02 per million input tokens, and the v1.1 weights are public under Apache-2.0. The API is days old, the official Python SDK has no method for it, and the governing terms and privacy notice could not be read on 9 October 2026.

## Before you call either

### Liquid d1

1. POST to https://api.liquid.ai/decisions/v1/systemone with a `liquid_` key as a Bearer header. This is not a chat-completions endpoint
2. Use `d1` for images. `d1:free` is text-only and answers that it does not accept images
3. Send images as Base64 data URLs in `images`, at most 8, with the whole JSON body under 4.5 MB. Remote image URLs are refused
4. Budget tokens per question. Each question is billed as its own prompt, with its text and every image counted again
5. Don't send confidential content to the hosted API, since the terms allow training on it. Run d1-3B locally for that data

### pplx-decider

1. Send `Authorization: Bearer`. A key in `x-api-key` returns 401 on this endpoint.
2. Set `model` on every request. A missing or unknown model returns 400, and the guide shows a `-latest` name rejected.
3. Resize images to 2,048 tiles of 32 by 32 pixels or fewer before sending. Larger images end in a 504 after about a minute.
4. Check the HTTP status before parsing an error. 404 and 405 have empty bodies, 504 can be HTML, and `error.code` changes type.
5. For the weights, use the repository's `autojev` code. The card says default causal inference does not reproduce the evaluated setup.

## Questions

### Which is better for AI agents, Liquid d1 or pplx-decider?

pplx-decider scores 62.9 (B) on agent readiness against Liquid d1's 43.5 (E), and leads in 5 of 7 scored categories.

### Do Liquid d1 and pplx-decider need an API key?

Both need an API key.

### Can an agent call Liquid d1 and pplx-decider without installing anything?

Yes. Liquid d1 has a hosted endpoint at https://api.liquid.ai/decisions/v1/systemone and pplx-decider at https://api.perplexity.ai/v1/decisions.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/liquid-d1-vs-pplx-decider.json, and with the fewest tokens: https://www.anchorterminal.com/compare/liquid-d1-vs-pplx-decider.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "liquid-d1", "b": "pplx-decider"}`. From a terminal: `anchor compare liquid-d1 pplx-decider`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/liquid-d1.json and https://www.anchorterminal.com/api/v1/tools/pplx-decider.json

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- [Celeris-1 Decision vs Liquid d1](https://www.anchorterminal.com/compare/celeris-1-decision-vs-liquid-d1.md)
- [Celeris-1 Decision vs pplx-decider](https://www.anchorterminal.com/compare/celeris-1-decision-vs-pplx-decider.md)
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