# NVIDIA NeMo Guardrails vs ShieldGemma

> NVIDIA NeMo Guardrails scores 69.5 (B) to ShieldGemma's 54 (C) for content moderation. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-11-07

NVIDIA NeMo Guardrails scores 69.5 (B) on agent readiness against ShieldGemma's 54 (C), and leads in 6 of 7 scored categories. ShieldGemma leads on agent ergonomics. Both do content moderation.

- NVIDIA NeMo Guardrails: grade B, 69.5/100, rank #241 of 1510. Markdown https://www.anchorterminal.com/tools/nemo-guardrails.md · JSON https://www.anchorterminal.com/api/v1/tools/nemo-guardrails.json
- ShieldGemma: grade C, 54/100, rank #927 of 1510. Markdown https://www.anchorterminal.com/tools/shieldgemma.md · JSON https://www.anchorterminal.com/api/v1/tools/shieldgemma.json
- Best guardrails and safety filters for AI agents: https://www.anchorterminal.com/best/guardrails/index.md
- All 155 guardrails comparisons: https://www.anchorterminal.com/compare/guardrails/index.md

## Which one, for what

### NVIDIA NeMo Guardrails (B)

Good for: Teams that want to compose several checks (their own, NVIDIA's and third-party APIs) behind one OpenAI-compatible endpoint.

Ahead on:
- Reliability, 75 against 46
- Schema & documentation, 79 against 56
- Security & auth, 62 against 53
- Payments & pricing, 60 against 52
- Maintenance & community, 70 against 40
- Transparency & trust, 72 against 54

Also in its favour:
- Open source

Watch for: Usage telemetry and a heartbeat every 10 minutes to NVIDIA by default

### ShieldGemma (C)

Good for: Policy-specific content moderation of English text input or output, or of images, on the owner's hardware, with a probability to threshold.

Ahead on:
- Agent ergonomics, 72 against 67

Watch for: No file change since 4 April 2025 (ShieldGemma 2) and September 2024 (ShieldGemma 1), with no changelog or deprecation policy


## Why the edge

### Maintenance & community: NVIDIA NeMo Guardrails +30

- NVIDIA NeMo Guardrails (70): 0.24.1 on 16 September 2026, 46 days before the check, with no release since in the repository's tags (20). Two releases in the 90 days from 3 August, 0.24.0 on 25 August and 0.24.1, with 0.23.0 on 1 July outside (10 of 20, our batch rule for two). 71 commits on develop since 0.24.1, the last on 30 October, are unreleased. Issues get triage labels, but about a dozen opened in August read needs triage, per the 1 October check, not re-read on 1 November (15 of 25). Current package on PyPI, per the 1 October check (15). CI on three operating systems and supported runtimes stated (10). 20+10+15+15+10 = 70.
- ShieldGemma (40): Read as a model, on the lines used for Granite Guardian (recency 30, deprecation 12, churn 8, responsiveness 25, packages 15, health 10). The newest file change is ShieldGemma 2 on 4 April 2025, 19 months before the check, and ShieldGemma 1 last changed in September 2024 (0 of 30). No deprecation policy. Both generations stay downloadable, and the ai.google.dev page was marked deprecated with a pointer to gemma.ai without dates for the models (3 of 12). Two generations in 2024 and 2025, each in its own repository, none replaced in place (6 of 8). Google accounts (members of Google's Gemma organisations on the Hub) answered every thread we sampled on the 2B, 9B and ShieldGemma 2 pages, from August 2024 to 22 March 2026, but leave most threads open (16 of 25). Transformers, Keras and Ollama's library load it (12 of 15). No CI, and Ollama's library build was last updated 2 years ago (3 of 10). 0 + 3 + 6 + 16 + 12 + 3 = 40.

### Reliability: NVIDIA NeMo Guardrails +29

- NVIDIA NeMo Guardrails (75): Local framework reading. Installs from PyPI as nemoguardrails, pyproject on develop states Python 3.10 to 3.13 (20). The README carries passing badges for tests on Linux, Windows and macOS and for lint on the develop branch, per the 1 October check, not re-read on 1 November (25). About 140 open issues and 80 to 100 open pull requests, with bug reports from August 2026 still labelled needs triage beside others already triaged, per the 1 October check, not re-read on 1 November (15 of 25). The changelog follows Keep a Changelog and marks breaking items, six of them in 0.24.0 (15). Version 0.24.1, not 1.0, and develop now reads 0.25.0-rc1, unreleased (0).
- ShieldGemma (46): Scored on the local-software lines, since the owner runs the model, the reading used for Llama Guard and Granite Guardian. Google's install line is `pip install -U transformers[accelerate]` with no versions, a Keras Colab notebook covers ShieldGemma 1, and Ollama's own library carries ShieldGemma 1. No Python version or memory figure is stated, and the publisher's files sit behind a login and licence click-through (12 of 20). No CI, tests or evaluation code for the models were found. The technical reports describe the evaluation and nothing reruns it (0 of 25). On the Hub, 8 of 23 threads on the 2B, 2 of 10 on the 9B, none of 8 on the 27B and 9 of 10 on ShieldGemma 2 are open, but every open thread we sampled has a reply from a Google account, the newest on 22 March 2026 (15 of 25). No changelog or version tags. The two generations are named and sit in their own repositories (4 of 15). Released with no preview label (15 of 15). 12 + 0 + 15 + 4 + 15 = 46.

### Schema & documentation: NVIDIA NeMo Guardrails +23

- NVIDIA NeMo Guardrails (79): Framework reading. Rail configuration is typed in Python and validated on load, and the server speaks the OpenAI chat-completions shape. The repository holds a Fern OpenAPI file, generated at docs build time since 23 October 2026, but no published OpenAPI document for /v1/checks was found in the docs (15 of 25). The docs serve llms.txt at docs.nvidia.com/nemo/guardrails/llms.txt, with a 681-line index of Markdown pages for the latest version and one per release from 0.22.0 (10). The docs describe each rail type and the built-in and third-party rails, and 0.24.0 added IORails, which runs input and output rails without the Colang runtime (15 of 20). YAML configuration with typed models, though Colang 1 and Colang 2 coexist (12 of 15). An examples tree in the repository and per-rail guides, little on error responses (12 of 15). Semver releases and a dated changelog (15). 15+10+15+12+12+15 = 79.
- ShieldGemma (56): Read for a model the owner serves. There is no specification of its own. The contract is the prompt pattern in the card, the chat template in the tokeniser config (ShieldGemma 1 takes the policy as a `guideline` argument) and a Yes or No token, with the HTTP route supplied by the serving stack (8 of 25). gemma.ai/llms.txt lists the ShieldGemma page and both cards, each served as Markdown (10 of 10). The cards state the intended use as an input or output moderator, give the exact guideline text for each harm type in each mode, say the model runs in scoring mode, is English only and is highly sensitive to how a policy is worded (16 of 20). Fixed harm types and a binary answer, with the policy as free text (10 of 15). A Transformers snippet for each generation and a Keras notebook. No failure modes or error cases are documented (8 of 15). Two named generations with no changelog, and the ai.google.dev page is marked deprecated in favour of gemma.ai (4 of 15). 8 + 10 + 16 + 10 + 8 + 4 = 56.

### Transparency & trust: NVIDIA NeMo Guardrails +18

- NVIDIA NeMo Guardrails (72): Apache-2.0 with a third-party licence file (30). The telemetry page lists what's sent (version, configuration, which capabilities are switched on, deployment type) and what isn't (prompts, completions, messages, keys, endpoints). We didn't read the code to confirm it (25 of 30). Breaking items are marked per release, but there's no deprecation policy with dates (12 of 20). Telemetry with heartbeats every 10 minutes is on by default, opt-out with NEMO_GUARDRAILS_NO_USAGE_STATS=1, DO_NOT_TRACK=1 or a do_not_track file, and off in CI (15 of 20).
- ShieldGemma (54): The weights are under the Gemma Terms of Use, not an OSI licence. They carry distribution conditions, the Prohibited Use Policy and a clause that lets Google restrict usage remotely where it believes the terms are breached. The terms are dated (1 April 2026) with earlier versions archived (15 of 30). Inputs stay on the owner's hardware, so no privacy statement applies. ShieldGemma 1 was fine-tuned on synthetic internal data and public datasets described in a technical report, and ShieldGemma 2 on a WebLI subset and synthetic images with CSAM filtering. No data is released (20 of 30). No deprecation policy or dated model retirements (5 of 20). The weights carry no telemetry of their own, with no statement either way, and downloads go through Hugging Face, Kaggle or Ollama (10 of 20). 15 + 20 + 5 + 10 = 50.

### Security & auth: NVIDIA NeMo Guardrails +9

- NVIDIA NeMo Guardrails (62): Framework reading. No auth of its own, and SECURITY.md says authentication, authorisation, TLS and rate limiting are the deployer's job. Provider keys come from the environment (10 of 30). Tool-input and tool-output rails can block a tool call, but there's no human approval hook, and the LLM-judged tool_safety_check is only on develop since 29 September 2026 (12 of 20). Jailbreak heuristics and model, injection detection and content-safety rails, documented (15). OpenTelemetry tracing to your own backend, opt-in (12 of 15). Disclosure through NVIDIA PSIRT, no bug bounty, no published advisories, and usage telemetry to NVIDIA on by default with a documented opt-out (13 of 20).
- ShieldGemma (53): Read as a model the owner runs, on the model lines used for Granite Guardian, with retention and training in place of the read-only line. No key is needed to run it. Google's files need a Hugging Face login and licence acceptance, approved immediately, so there is a token to download but no secret at run time (13 of 30). Self-hosted, so inputs stay on the owner's hardware and nothing reaches Google, though no Google page says so (15 of 20). It reads untrusted text by design. The card says the model is highly sensitive to the policy wording and may behave unpredictably with ambiguous language, and gives no prompt-injection guidance (6 of 15). No call log of its own, though each call returns a score (5 of 15). Weights are safetensors only and load through Transformers classes with no remote code. Google's security.txt is valid and points to its reward programme, and there is no model-specific security page or advisory record (14 of 20). 13 + 15 + 6 + 5 + 14 = 53.

### Payments & pricing: NVIDIA NeMo Guardrails +8

- NVIDIA NeMo Guardrails (60): Apache-2.0 package you run yourself with nothing to buy from the project, so 20 for pricing, 20 for a free start and 20 for keyless use. No payment protocol (0). The NemoGuard models it can call are priced separately by NVIDIA.
- ShieldGemma (52): Self-hosted rule. Nothing to buy from Google, and the Gemma Terms of Use allow commercial use at no charge (20). Free to run with no card (20). Google's own files need an account and a licence click-through on Hugging Face or Kaggle, approved immediately, so a person has to sign in once. Ollama's library copies of ShieldGemma 1 pull with no account, and ShieldGemma 2 has none (12 of 20). No payment protocol (0). No hosted ShieldGemma from Google or an inference provider was found. 20 + 20 + 12 + 0 = 52.

## Score by category

| Category | Weight | NVIDIA NeMo Guardrails | ShieldGemma | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 75 | 46 | NVIDIA NeMo Guardrails +29 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 79 | 56 | NVIDIA NeMo Guardrails +23 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 72 | ShieldGemma +5 |
| Security & auth | 14% (17.5 this run) | 62 | 53 | NVIDIA NeMo Guardrails +9 |
| Payments & pricing | 10% (12.5 this run) | 60 | 52 | NVIDIA NeMo Guardrails +8 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 70 | 40 | NVIDIA NeMo Guardrails +30 |
| Transparency & trust | 7% (8.8 this run) | 72 | 54 | NVIDIA NeMo Guardrails +18 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **69.5 · B** | **54 · C** | |

## Facts side by side

| Fact | NVIDIA NeMo Guardrails | ShieldGemma |
| --- | --- | --- |
| Kind | Agent framework | Model API |
| Vendor | NVIDIA | Google DeepMind |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | HTTP |  |
| Auth | None | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | Apache-2.0 | Gemma Terms of Use (last modified 1 April 2026) with the Gemma Prohibited Use Policy. Not an OSI licence |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-09-16 | 2025-04-04 |
| Terms last updated | couldn't be read | 2026-04-01 |
| Privacy policy last updated | no date given | no document linked |
| Customer content may train models | couldn't be read | yes |
| Terms restrict automated access | couldn't be read | not found in the text |
| Terms restrict benchmarking | couldn't be read | not found in the text |
| Terms or service can change without notice | couldn't be read | not found in the text |
| Arbitration or class-action waiver | couldn't be read | not found in the text |
| Popularity | 7.2k stars, 101k PyPI/wk | none |
| Agent reviews | 3/5 (2) | none |

## How the scores have moved

### NVIDIA NeMo Guardrails

- +0.7 on 1 November 2026: new evidence, time
- +0.4 on 27 October 2026: checklist
- -0.3 on 8 October 2026: checklist

### ShieldGemma

No score change since it was listed.

## Verdicts

**NVIDIA NeMo Guardrails.** Apache-2.0, 7,200 stars and nine releases between 9 October 2025 and 16 September 2026. Usage telemetry and a heartbeat every 10 minutes to NVIDIA by default.

**ShieldGemma.** Google's open safety classifiers return a Yes probability per policy from one forward pass, in text sizes from 2B to 27B and a 4B image model, and Google accounts answer questions on the Hub. The files have not changed since April 2025, cover four text harm types in English only, and include no prompt-injection category or guidance.

## Before you call either

### NVIDIA NeMo Guardrails

1. Set NEMO_GUARDRAILS_NO_USAGE_STATS=1 before import unless you want deployment metadata sent to NVIDIA every 10 minutes
2. Use IORails for plain input and output checks. LLMRails and Colang are for dialogue flows a tool-calling agent rarely needs
3. Pin nemoguardrails==0.24.1. 0.24.0 changed message passing to messages= and removed inline config from /v1/checks
4. Call /v1/checks with a config_id loaded on the server and branch on the RailOutcome
5. Put the server behind your own gateway. It has no auth or rate limiting

### ShieldGemma

1. Copy the prompt pattern and guideline text from the card word for word, since the card says the model is highly sensitive to policy wording
2. Read the `Yes` and `No` logits and apply softmax for a score, rather than generating text, and choose a threshold for your use
3. Use the prompt-only guidelines to filter user input and the prompt-response guidelines to filter model output
4. Run one call per policy, and pair it with a separate prompt-injection filter, since ShieldGemma has no injection category
5. Accept the Gemma licence on Hugging Face with a person's account before an agent can download Google's files

## Questions

### Which is better for AI agents, NVIDIA NeMo Guardrails or ShieldGemma?

NVIDIA NeMo Guardrails scores 69.5 (B) on agent readiness against ShieldGemma's 54 (C), and leads in 6 of 7 scored categories. ShieldGemma leads on agent ergonomics.

### Can an agent call NVIDIA NeMo Guardrails and ShieldGemma without installing anything?

No hosted endpoint is listed for NVIDIA NeMo Guardrails. No hosted endpoint is listed for ShieldGemma.

### Are NVIDIA NeMo Guardrails and ShieldGemma open source?

NVIDIA NeMo Guardrails is open source (Apache-2.0). No open-source release is listed for ShieldGemma.


## For agents

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

## Other comparisons with NVIDIA NeMo Guardrails or ShieldGemma

- [Amazon Bedrock Guardrails vs ShieldGemma](https://www.anchorterminal.com/compare/amazon-bedrock-guardrails-vs-shieldgemma.md)
- [Azure AI Content Safety (Prompt Shields) vs ShieldGemma](https://www.anchorterminal.com/compare/azure-ai-content-safety-vs-shieldgemma.md)
- [Cisco AI Defense Inspection API vs ShieldGemma](https://www.anchorterminal.com/compare/cisco-ai-defense-inspection-vs-shieldgemma.md)
- [Google Cloud Model Armor vs ShieldGemma](https://www.anchorterminal.com/compare/google-model-armor-vs-shieldgemma.md)
- [Granite Guardian vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/granite-guardian-vs-nemo-guardrails.md)
- [Granite Guardian vs ShieldGemma](https://www.anchorterminal.com/compare/granite-guardian-vs-shieldgemma.md)
- [Guardrails AI vs ShieldGemma](https://www.anchorterminal.com/compare/guardrails-ai-vs-shieldgemma.md)
- [Lakera Guard (Check Point AI Guardrails) vs ShieldGemma](https://www.anchorterminal.com/compare/lakera-guard-vs-shieldgemma.md)
- [Llama Guard 4 vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/llama-guard-vs-nemo-guardrails.md)
- [Llama Guard 4 vs ShieldGemma](https://www.anchorterminal.com/compare/llama-guard-vs-shieldgemma.md)
- [Mistral Moderation API vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/mistral-moderation-vs-nemo-guardrails.md)
- [Mistral Moderation API vs ShieldGemma](https://www.anchorterminal.com/compare/mistral-moderation-vs-shieldgemma.md)
- [NVIDIA NeMo Guardrails vs OpenAI Moderation API](https://www.anchorterminal.com/compare/nemo-guardrails-vs-openai-moderation.md)
- [OpenAI Guardrails vs ShieldGemma](https://www.anchorterminal.com/compare/openai-guardrails-vs-shieldgemma.md)
- [OpenAI Moderation API vs ShieldGemma](https://www.anchorterminal.com/compare/openai-moderation-vs-shieldgemma.md)
- [Prisma AIRS AI Runtime Security API vs ShieldGemma](https://www.anchorterminal.com/compare/prisma-airs-vs-shieldgemma.md)
- [Amazon Bedrock Guardrails vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/amazon-bedrock-guardrails-vs-nemo-guardrails.md)
- [Azure AI Content Safety (Prompt Shields) vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/azure-ai-content-safety-vs-nemo-guardrails.md)
- [Cisco AI Defense Inspection API vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/cisco-ai-defense-inspection-vs-nemo-guardrails.md)
- [Google Cloud Model Armor vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/google-model-armor-vs-nemo-guardrails.md)
- [Guardrails AI vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/guardrails-ai-vs-nemo-guardrails.md)
- [Lakera Guard (Check Point AI Guardrails) vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/lakera-guard-vs-nemo-guardrails.md)
- [LlamaFirewall vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/llamafirewall-vs-nemo-guardrails.md)
- [NVIDIA NeMo Guardrails vs OpenAI Guardrails](https://www.anchorterminal.com/compare/nemo-guardrails-vs-openai-guardrails.md)
- [NVIDIA NeMo Guardrails vs Prisma AIRS AI Runtime Security API](https://www.anchorterminal.com/compare/nemo-guardrails-vs-prisma-airs.md)
- [AgentGate vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/agentgate-vs-nemo-guardrails.md)
- [AgentGate vs ShieldGemma](https://www.anchorterminal.com/compare/agentgate-vs-shieldgemma.md)
- [LlamaFirewall vs ShieldGemma](https://www.anchorterminal.com/compare/llamafirewall-vs-shieldgemma.md)
- [Presidio vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/microsoft-presidio-vs-nemo-guardrails.md)
- [Presidio vs ShieldGemma](https://www.anchorterminal.com/compare/microsoft-presidio-vs-shieldgemma.md)

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