Nightfall AI alternative for LLM API calls: replace, not block

Nightfall AI is a data loss prevention platform. It blocks or monitors what breaks a policy across SaaS apps, email, endpoints, browsers and AI agents. It does not swap personal data out of a prompt and put it back into the answer: model responses can only be monitored.

Nonimo Gateway runs on your own servers. See plans and get in touch.

If you are a developer calling the OpenAI API from your own application, and you want names and numbers replaced on the way out and restored on the way back so the task still gets done, you need a tool of a different shape. This guide sets out what Nightfall publishes and where Nonimo Gateway fits.

What Nightfall does with data sent to AI

Nightfall is employee-wide DLP: one console across SaaS apps, email, endpoints, browsers and coding agents.

Its documentation on choosing a control says what each AI hook can do.

Hook type	When it runs	Can it block?
User prompts	When the user sends a prompt	Yes
Tool calls	Before an MCP tool or subagent runs	Yes
Model responses	When the model answers	No, monitor only

The model is a gate. A prompt that contains a client’s tax number is stopped or flagged, not rewritten so the task can continue. For a lawyer who needs a summary of a client letter, a blocked prompt is a task that does not get done, and people find another way to do it. Our guide on whether putting client data in ChatGPT is a data breach explains why that other way is the real risk.

Where Nightfall does not fit an API round trip

• No restore. The Developer API can mask, substitute or encrypt findings with your RSA public key, and the redaction docs leave any decryption to you. No automatic restore into an LLM’s answer is documented.
• Not an OpenAI-compatible proxy. We found no such endpoint as of 20 October 2026.
• Not self-hosted. It integrates with SaaS apps by OAuth and reaches laptops through agents rolled out by MDM. No page we read offers an on-premises installation or a container you run.
• English-centric meaning. Its language FAQ says it has no semantic understanding of text unless it is in English or trained for the case, with local-language context for some numeric detectors such as the Brazilian CPF.
• Price not shown. The pricing page shows a price per user per year without the amount, with a free 7-day proof of value. The Developer Platform has a free plan of 3 GB scanned a month.

If your documents are in Spanish, German or French and the identifiers are national, test with your own samples. Our list of what personal information to remove before AI is a starting point for that test set.

DLP or an API proxy

	Nightfall	Nonimo Gateway
Who it protects	Employees across SaaS apps, email, endpoints, browsers and AI agents	Your own application’s calls to an LLM API
What it does with sensitive data	Blocks or monitors by policy; API can mask, substitute or encrypt	Replaces it in the request and restores it in the response
Model responses	Monitor only	Real values back in the answer
Where it runs	Nightfall’s cloud, with agents and extensions on laptops	On your own servers
How it is rolled out	OAuth, MDM, hooks	Change base_url in your OpenAI client
Pricing model	Per user per year, quoted	Plans on the Nonimo Gateway page, with your own OpenAI key

If the question is “what are our 80 staff pasting into chatbots, Slack and email”, that is DLP. If it is “how does the intake tool our developer built send client letters to GPT without the names”, that is a proxy. For staff who paste into ChatGPT in a browser, the Nonimo desktop app is a different product again. For the wider field, see Protecto, Limina, formerly Private AI, and our overview of PII redaction software.

How Nonimo Gateway does it

Nonimo Gateway is a private proxy for applications that call the OpenAI API with their own key. It runs on your own servers and is OpenAI-compatible, so your code changes one line:

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://gateway.your-company.internal/v1",  # your Nonimo Gateway
    api_key=os.environ["OPENAI_API_KEY"],                  # your own OpenAI key
)

It replaces personal data in what goes out and restores the real values in the response, so the user reads the real names while the model works with placeholders. It recognises the national documents and numbers of each country it serves, such as the Spanish DNI, NIE and NIF, the German Steuer-ID, the French NIR, the Italian codice fiscale and the Brazilian CPF. There is a plugin for LiteLLM if that is how you route model calls.

Before you choose, write the rule: which data may go to which AI tool. Our AI policy template gives you the structure, and the same answers feed the AI questions on a cyber insurance questionnaire.

If the gap is your own application’s API traffic, and blocking would stop work that has to happen, Nonimo Gateway replaces and restores instead. See plans and get in touch on the Gateway page.

Sources

Checked 20 October 2026.

• Nightfall, homepage. Positioning and inspection of prompts, tool calls and responses.
• Nightfall, pricing. Per user per year without amount, the 7-day proof of value.
• Nightfall Help, deploying Nightfall. OAuth integration into SaaS apps.
• Nightfall Help, index. Endpoint agents for macOS and Windows and MDM guides.
• Nightfall Help, choosing a control. Hook types, block or monitor, monitor-only responses.
• Nightfall Developer API, overview. Redacting, substituting or encrypting sensitive text.
• Nightfall Developer API, redaction. The redaction modes and RSA encryption, with decryption left to you.
• Nightfall Developer API, pricing. The free plan of 3 GB scanned per month.
• Nightfall Help, supported languages. English-centric semantic detection and local-language context for some detectors.

---

This page is for information. Product details of other vendors were checked on their official pages on 20 October 2026 and can change.