# Liquid d1 vs Drex 1.5

> Drex 1.5 scores 69.7 (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-nace-drex
- Markdown: https://www.anchorterminal.com/compare/liquid-d1-vs-nace-drex.md (~2,600 tokens)
- Slim: https://www.anchorterminal.com/compare/liquid-d1-vs-nace-drex.min.md (~830 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/liquid-d1-vs-nace-drex.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: 2026-10-10

Drex 1.5 scores 69.7 (B) on agent readiness against Liquid d1's 43.5 (E), and leads in every scored category. Both do decision models.

- Liquid d1: grade E, 43.5/100, rank #886 of 954. Markdown https://www.anchorterminal.com/tools/liquid-d1.md · JSON https://www.anchorterminal.com/api/v1/tools/liquid-d1.json
- Drex 1.5: grade B, 69.7/100, rank #172 of 954. Markdown https://www.anchorterminal.com/tools/nace-drex.md · JSON https://www.anchorterminal.com/api/v1/tools/nace-drex.json
- Best decision models for AI agents: https://www.anchorterminal.com/best/decision-models/index.md
- All 91 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

### Drex 1.5 (B)

Good for: Routing, triage and yes or no gates inside an agent, where the caller supplies the options and acts on the probabilities. Suited to hosted use at a low per-token price, or to open weights where the licence fits.

Ahead on:
- Reliability, 80 against 21
- Schema & documentation, 88 against 59
- Agent ergonomics, 85 against 63
- Security & auth, 65 against 35
- Payments & pricing, 40 against 27
- Maintenance & community, 65 against 60
- Transparency & trust, 63 against 54

Watch for: The rank 1 claim comes from Nace's own run on Decision Index 0.3.1, and Drex is not on the public board for 0.3 or 0.2.1.


## Score by category

| Category | Weight | Liquid d1 | Drex 1.5 | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 21 | 80 | Drex 1.5 +59 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 59 | 88 | Drex 1.5 +29 |
| Agent ergonomics | 13% (16.2 this run) | 63 | 85 | Drex 1.5 +22 |
| Security & auth | 14% (17.5 this run) | 35 | 65 | Drex 1.5 +30 |
| Payments & pricing | 10% (12.5 this run) | 27 | 40 | Drex 1.5 +13 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 65 | Drex 1.5 +5 |
| Transparency & trust | 7% (8.8 this run) | 54 | 63 | Drex 1.5 +9 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **43.5 · E** | **69.7 · B** | |

## Facts side by side

| Fact | Liquid d1 | Drex 1.5 |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Liquid AI | Nace AI, Inc. (Nace.AI) |
| Hosted endpoint | `https://api.liquid.ai/decisions/v1/systemone` | `https://console.nace.ai/v1/systemone` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| 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 | Hosted API under the Nace AI Terms of Service, last updated 5 May 2026. Weights under the Nace AI Open RAIL-M licence (modified, version 1.0, October 2026), which is not an open-source licence. Businesses above $1 million in revenue or funding need a separate commercial licence, and competing products are excluded. The bundled code/kev package, derived from Jared Palmer's Kev (https://github.com/jaredpalmer/kev), and the GitHub repository are Apache-2.0, and the agent skill is MIT. |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-07 | 2026-09-28 |
| Terms last updated | 2026-09-30 |  |
| Privacy policy last updated | 2026-09-30 |  |
| Customer content may train models | yes |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | none | 318 npm/wk, 156 PyPI/wk |

## 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.

**Drex 1.5.** The hosted endpoint has a public OpenAPI document, published limits and pinned model versions, at $0.05 per million input tokens with no output charge. The #1 under 10B claim rests on Nace's own run, since Drex is absent from both public boards. Weights carry Open RAIL-M, which requires a commercial licence above $1 million in revenue or funding.

## 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

### Drex 1.5

1. Call https://console.nace.ai/v1/systemone with Authorization: Bearer nace_sk_..., and pin model drex-v1.5 rather than drex-latest in production.
2. Stop on 402 insufficient_credit or 402 payment_required until credit is topped up or the unpaid invoice is paid.
3. Retry 429 and 529 after retry-after-ms. On a 422 for an unknown model, use one of the ids the error message lists.
4. Keep state below 131,072 tokens and the body below 1,048,576 bytes, and send at most 512 questions per request.
5. Keep the key on a server. A key in browser code is exposed, and the /v1 routes send no Access-Control-Allow-Origin header.
6. Check usage.input_tokens and the usage CSV after retries, since /v1/systemone documents no idempotency key.

## Questions

### Which is better for AI agents, Liquid d1 or Drex 1.5?

Drex 1.5 scores 69.7 (B) on agent readiness against Liquid d1's 43.5 (E), and leads in every scored category.

### Do Liquid d1 and Drex 1.5 need an API key?

Both need an API key.

### Can an agent call Liquid d1 and Drex 1.5 without installing anything?

Yes. Liquid d1 has a hosted endpoint at https://api.liquid.ai/decisions/v1/systemone and Drex 1.5 at https://console.nace.ai/v1/systemone.


## For agents

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

## Other comparisons with Liquid d1 or Drex 1.5

- [Celeris-1 Decision vs Liquid d1](https://www.anchorterminal.com/compare/celeris-1-decision-vs-liquid-d1.md)
- [Celeris-1 Decision vs Drex 1.5](https://www.anchorterminal.com/compare/celeris-1-decision-vs-nace-drex.md)
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- [Kev vs Drex 1.5](https://www.anchorterminal.com/compare/jaredpalmer-kev-vs-nace-drex.md)
- [Liquid d1 vs Microsoft-Decision-1](https://www.anchorterminal.com/compare/liquid-d1-vs-microsoft-decision-1.md)
- [Liquid d1 vs OpenAI Decisions API](https://www.anchorterminal.com/compare/liquid-d1-vs-openai-decisions-api.md)
- [Liquid d1 vs pplx-decider](https://www.anchorterminal.com/compare/liquid-d1-vs-pplx-decider.md)
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- [Liquid d1 vs Jev](https://www.anchorterminal.com/compare/liquid-d1-vs-typesafe-jev.md)
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- [Microsoft-Decision-1 vs Drex 1.5](https://www.anchorterminal.com/compare/microsoft-decision-1-vs-nace-drex.md)
- [Drex 1.5 vs OpenAI Decisions API](https://www.anchorterminal.com/compare/nace-drex-vs-openai-decisions-api.md)
- [Drex 1.5 vs pplx-decider](https://www.anchorterminal.com/compare/nace-drex-vs-pplx-decider.md)
- [Drex 1.5 vs Strands Decider 2B](https://www.anchorterminal.com/compare/nace-drex-vs-strands-decider.md)
- [Drex 1.5 vs Jev](https://www.anchorterminal.com/compare/nace-drex-vs-typesafe-jev.md)
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