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Not Diamond
Not Diamond is a software company whose model router picks the best large language model for each request in coding agents and other AI applications, working alongside a team's existing gateway and harness, and whose Prompt Adaptation product rewrites prompts to suit a new model.
Engineering teams with coding agents or high-volume LLM workloads spread across several models, who want routing and cost control added on top of the gateway and harness they already use.
Teams looking for one product that handles logging, key management, budgets, and routing together, and buyers who need published enterprise terms before a first call.
Verdict
Not Diamond is worth a look when model spend is the pain. It posts a flat routing price of $0.05 per million tokens, claims a 5% accuracy gain and 50% cost savings on its homepage, and lists SOC 2 and ISO 27001. It is a router rather than a gateway, so it sits beside tools like LiteLLM, Portkey, and Helicone instead of replacing them.
Score Breakdown
These scores cover how well Not Diamond routes requests, how it fits with the gateways and harnesses teams already run, how it protects data, and how it helps teams move to new models, and then how it does as a company on innovation, communication, pricing, and contract terms.
Who Uses Not Diamond, Where It Fits on Price, and Its Competitors
Not Diamond is a model router: for each request it chooses which large language model should answer, aiming to keep accuracy up while cutting cost, and its homepage frames the product around coding agents. The router plugs into a team's existing harness and gateway rather than replacing them, and the company says it adds 100 to 150 milliseconds of latency. A second product, Prompt Adaptation, rewrites prompts so that a prompt tuned for one model works on another. Not Diamond's homepage carries testimonials from OpenRouter, Replicated, and Rootly.
Not Diamond charges pay as you go at $0.05 per million tokens routed, with a custom Enterprise plan that adds volume discounts, SAML single sign-on, and privacy-preserving deployment. Its closest competitors are LiteLLM, Portkey, and Helicone, which are gateways that proxy model calls, and PromptLayer, which versions and logs prompts.
Pricing
We checked Not Diamond's pricing page and recorded one pay-as-you-go rate and a custom Enterprise plan.
| Plan | Price | What stands out |
|---|---|---|
| Pay as you go | $0.05 per million tokens routed | Billed on the tokens the router handles, on top of what a team pays its model providers. Not Diamond's pricing page says teams typically save at least 20 to 40%, a company estimate we could not verify. |
| Enterprise | Custom | Adds volume discounts, SAML single sign-on, and privacy-preserving deployment. |
| Security | Included | SOC 2 and ISO 27001, with privacy-preserving routing, according to Not Diamond. |
The Field at a Glance
How Not Diamond compares with other prompt and app framework vendors we reviewed, by Overall Score and relative typical engagement cost.
Not Diamond scores 7.4 in prompt and app framework, under LiteLLM (8.0), Portkey (7.9), and Helicone (7.8), and ahead of PromptLayer (6.9) and Promptfoo (6.7).
Compared with …
- Not Diamond vs LiteLLM 7.4/8.0
How Well Not Diamond Fits Each Model Routing Use Case
We rated Not Diamond against the situations engineering teams bring to a model router, drawing on its homepage, pricing page, about page, and May 2025 press release.
| Use case | Fit | Notes |
|---|---|---|
| Cutting model spend in coding agents | Strong | The homepage claims a 5% accuracy gain and 50% cost savings, and the pricing page cites at least 20 to 40%, all company figures. |
| Adding routing to an existing gateway | Strong | The router integrates with a team's existing harness and gateway, and Not Diamond describes this as protection against vendor lock-in. |
| Moving prompts to a new model | Strong | Prompt Adaptation, launched in May 2025, rewrites prompts so they perform on a different model. |
| Regulated or privacy-sensitive workloads | Mixed | SOC 2 and ISO 27001 and privacy-preserving routing are listed, and detailed deployment terms sit behind the Enterprise plan. |
| One tool for keys, budgets, and logging | Weak | Not Diamond is a router, and the gateways it works beside carry those functions. |
| Buyers who want to see the whole bill | Mixed | The router rate is posted, and total spend also depends on the models the router chooses. |
Review Excerpts
These excerpts come from testimonials Not Diamond posts on its homepage, which the company chose, and from the buyer concern we found on its pricing page. Paid reviews and pay-for-play sites were excluded.
“We use Not Diamond to power our intelligent routing feature, giving developers the ability to automatically use the best model on every input across every leading language model.”
“Not Diamond significantly reduced our inference costs while also driving improvements in output quality. Throughout it all, the Not Diamond team has been incredibly responsive anytime we need support.”
“Across our SRE benchmarks, Not Diamond increased the average accuracy by 39%, with some use cases more than doubling in performance.”
“The router price is clear, but I can't tell from the pricing page what Enterprise costs or how the savings estimate was measured.”
Where customer reviews couldn't be found, our analysts attempted to give a voice to buyer sentiment, drawing on real information from review sites, forums, and product documentation.
Based on: Not Diamond pricing
Company Facts
- Founders
- Tomás Hernando Kofman (CEO), Tze-Yang Tung (CTO), and Jeffrey Akiki (COO) (Not Diamond about)
- Headquarters
- San Francisco, according to Not Diamond's May 2025 press release (PR Newswire)
- Funding
- A May 2025 round with IBM, SAP.iO Fund, Myriad Venture Partners, Deepwater, DNX Ventures, Ambush Capital, and Defy; the release we read does not state an amount (PR Newswire)
- Products
- Model router and Prompt Adaptation (Not Diamond)
- Security
- SOC 2 and ISO 27001 (Not Diamond pricing)
- Website
- notdiamond.ai
Key Leadership
Tomás Hernando Kofman
Co-founder and CEO
His AI Council speaker profile says he co-founded a housing startup that he worked on for four years through three funding rounds, and earlier built a civic tech platform that appeared on the cover of TIME (AI Council).
Tze-Yang Tung
Co-founder and CTO
Not Diamond's about page lists him as chief technology officer (Not Diamond about).
Jeffrey Akiki
Co-founder and COO
Not Diamond's about page lists him as chief operating officer (Not Diamond about).
Methodology
We scored Not Diamond on eight criteria, from routing quality to contract fairness, and the Overall Score is their simple average on a 0 to 10 scale. The scores draw on reviews from public review sites and forums, with paid reviews and pay-for-play sites excluded, plus a hands-on look at the product, its pricing, and its documentation and training. Scores can change as we add reviews and product checks.