# Drex 1.5 vs Vela 2.0

> Drex 1.5 scores 69.7 (B) to Vela 2.0's 66.5 (B) for decision models. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/nace-drex-vs-vela
- Markdown: https://www.anchorterminal.com/compare/nace-drex-vs-vela.md (~2,650 tokens)
- Slim: https://www.anchorterminal.com/compare/nace-drex-vs-vela.min.md (~780 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/nace-drex-vs-vela.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 Vela 2.0's 66.5 (B), and leads in 5 of 7 scored categories. Vela 2.0 leads on payments & pricing and maintenance & community. Both do decision models.

- 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
- Vela 2.0: grade B, 66.5/100, rank #291 of 954. Markdown https://www.anchorterminal.com/tools/vela.md · JSON https://www.anchorterminal.com/api/v1/tools/vela.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

### 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 57
- Schema & documentation, 88 against 78
- Agent ergonomics, 85 against 79
- Security & auth, 65 against 60
- Transparency & trust, 63 against 48

Also in its favour:
- A hosted endpoint, with nothing to install

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.

### Vela 2.0 (B)

Good for: Self-hosted routing and guardrail checks in one call, where span offsets for personal data or unsupported claims matter.

Ahead on:
- Payments & pricing, 60 against 40
- Maintenance & community, 84 against 65

Also in its favour:
- No key needed to call it
- Open source

Watch for: No version tags on the four Hub repositories, and the 4B and 9B weights were replaced in place on 3 October 2026


## Score by category

| Category | Weight | Drex 1.5 | Vela 2.0 | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 80 | 57 | Drex 1.5 +23 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 88 | 78 | Drex 1.5 +10 |
| Agent ergonomics | 13% (16.2 this run) | 85 | 79 | Drex 1.5 +6 |
| Security & auth | 14% (17.5 this run) | 65 | 60 | Drex 1.5 +5 |
| Payments & pricing | 10% (12.5 this run) | 40 | 60 | Vela 2.0 +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 65 | 84 | Vela 2.0 +19 |
| Transparency & trust | 7% (8.8 this run) | 63 | 48 | Drex 1.5 +15 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **69.7 · B** | **66.5 · B** | |

## Facts side by side

| Fact | Drex 1.5 | Vela 2.0 |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Nace AI, Inc. (Nace.AI) | vLLM Semantic Router project and KR Labs |
| Hosted endpoint | `https://console.nace.ai/v1/systemone` | no (local only) |
| Transports | HTTP | HTTP |
| Auth | API key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | 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. | Apache-2.0 (weights, code and documentation). The 0.3B's tokeniser keeps the Gemma Terms of Use, and training data keeps its own licences |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-09-28 | 2026-10-06 |
| Terms last updated |  | no document linked |
| Privacy policy last updated |  | no document linked |
| Customer content may train models |  |  |
| Terms restrict automated access |  |  |
| Terms restrict benchmarking |  |  |
| Terms or service can change without notice |  |  |
| Arbitration or class-action waiver |  |  |
| Popularity | 318 npm/wk, 156 PyPI/wk | 6.1k stars |

## Verdicts

**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.

**Vela 2.0.** One self-hosted call answers routing, prompt-attack, personal-data and unsupported-claim questions with probabilities and character offsets, under Apache-2.0 with SHA-256 manifests. The models are days old and carry no Hub version tags, and the three larger sizes keep 74 to 89 per cent of their Decision 2.0 bases on the Jev Decision Index by the authors' figures.

## Before you call either

### 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.

### Vela 2.0

1. Pin a commit hash with `revision=` when loading from the Hub. The repositories have no tags and `main` has changed since launch
2. Send the served name in `model`, for example `vllm-sr/Vela-2.0-4B`. The bundled server answers 422 to any other name
3. Name span questions `pii`, `halu` or `toxic`, or set `"head": "router"`, to get the trained router head. Other labels go to the broad head
4. Keep input under 16,384 tokens a sequence (8,192 on the 0.3B). The bundled server answers 413 when the questions alone don't fit
5. Set `VELA2_API_KEY` before binding the bundled server beyond 127.0.0.1, and keep the model runtime on a trusted network

## Questions

### Which is better for AI agents, Drex 1.5 or Vela 2.0?

Drex 1.5 scores 69.7 (B) on agent readiness against Vela 2.0's 66.5 (B), and leads in 5 of 7 scored categories. Vela 2.0 leads on payments & pricing and maintenance & community.

### Do Drex 1.5 and Vela 2.0 need an API key?

Drex 1.5 needs an API key. Vela 2.0 needs no key.

### Can an agent call Drex 1.5 and Vela 2.0 without installing anything?

Drex 1.5 has a hosted endpoint at https://console.nace.ai/v1/systemone. No hosted endpoint is listed for Vela 2.0.

### Are Drex 1.5 and Vela 2.0 open source?

No open-source release is listed for Drex 1.5. Vela 2.0 is open source (Apache-2.0 (weights, code and documentation). The 0.3B's tokeniser keeps the Gemma Terms of Use, and training data keeps its own licences).


## For agents

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

## Other comparisons with Drex 1.5 or Vela 2.0

- [Celeris-1 Decision vs Drex 1.5](https://www.anchorterminal.com/compare/celeris-1-decision-vs-nace-drex.md)
- [Celeris-1 Decision vs Vela 2.0](https://www.anchorterminal.com/compare/celeris-1-decision-vs-vela.md)
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- [Kev vs Drex 1.5](https://www.anchorterminal.com/compare/jaredpalmer-kev-vs-nace-drex.md)
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- [Microsoft-Decision-1 vs Drex 1.5](https://www.anchorterminal.com/compare/microsoft-decision-1-vs-nace-drex.md)
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- [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)
- [OpenAI Decisions API vs Vela 2.0](https://www.anchorterminal.com/compare/openai-decisions-api-vs-vela.md)
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- [Strands Decider 2B vs Vela 2.0](https://www.anchorterminal.com/compare/strands-decider-vs-vela.md)
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