PromptLayer

New York, NY, United States AI Infrastructure Private

PromptLayer is a prompt management, evaluation, and observability platform for teams building with large language models. The platform wraps LLM API calls to automatically capture prompts, versions, and outputs, enabling collaborative prompt engineering, version control, evaluation, and agent orchestration. PromptLayer positions itself for cross-functional teams, allowing non-technical domain experts to iterate on prompts alongside engineers.

Overview

Company data and valuation marks are estimates and may be incomplete, stale, erroneous, or revised.

Founded

2021

Employees

2–10

Total Funding

$4.8M

1 rounds

Funding

Total raised $4.8M across 1 rounds

Funding data and valuation marks are estimates and may be incomplete, stale, erroneous, or revised.

Last updated 06-25-2026

Latest Round

Type

Seed

Date

February 7, 2025

Amount

$4.8M

Valuation

Lead Investors

ScOp VCStellation Capital

Leadership

Competitors

Competitor list is illustrative and may be incomplete, stale, or erroneous.

  • LangSmith

    LLM observability and evaluation platform from LangChain, tightly integrated with the LangChain/LangGraph ecosystem for tracing, debugging, and monitoring agent workflows.

  • Langfuse

    Open-source LLM observability and prompt management platform offering tracing, evaluation, and prompt versioning with a self-hostable, SDK-based integration model.

  • Helicone

    Open-source LLM observability platform that uses a proxy-based integration to log requests, responses, and usage metrics for OpenAI/Anthropic API calls.

  • Braintrust

    End-to-end platform for evaluating, monitoring, and iterating on AI products with prompt versioning, evaluation, and observability tooling.

  • Weights & Biases

    Mature ML experiment tracking and developer infrastructure platform whose Weave product extends observability and evaluation to LLM applications.

  • Lunary

    Open-source LLM observability and analytics platform offering prompt management, evaluations, and conversation analytics for AI applications.

PromptLayer Investment FAQ

Public status and buying access

No. PromptLayer is a private company and does not have a public stock ticker or trade on a public stock exchange. Its shares are generally held by founders, employees, investors, and other private shareholders. Buyers and sellers may be able to transact in PromptLayer shares through private secondary transactions, but any transaction depends on share availability, buyer and seller agreement, transfer restrictions, company approval rights, and any applicable right of first refusal. There is no guarantee that PromptLayer will complete an IPO or other liquidity event.

Yes, it is sometimes possible to buy PromptLayer shares pre-IPO through private secondary transactions. This depends on finding a willing seller, company approval, and satisfying any transfer restrictions or rights of first refusal.

Buyers interested in buying PromptLayer shares on the secondary market typically do so through SetterVC and other secondary-market platforms, subject to eligibility requirements, share availability, transfer restrictions, and issuer approval. Buyers may need to satisfy sophistication, accreditation, institutional, platform, regulatory, or other eligibility requirements before participating. Once eligible, buyers may be able to view listings, make bids, and work with a licensed broker through the transaction process. Buyers should ensure they have appropriate legal and financial advisors guiding them before completing any transaction.

Valuation and funding

PromptLayer's latest disclosed funding round was a Seed round in February 7, 2025. The round raised approximately $4.8M, with ScOp VC and Stellation Capital listed as disclosed lead or major investors. Primary funding rounds are different from secondary transactions: in a primary round, capital goes to the company, while in a secondary transaction, investors buy existing shares from current shareholders. Funding-round data reflects publicly reported or collected information and may be incomplete.

PromptLayer has raised approximately $4.8M in disclosed funding across 1 round. These figures reflect primary capital raised by the company and do not include every possible secondary transaction, undisclosed round, debt facility, or private transfer. Reported funding totals can change as new rounds are announced or older round details are corrected. Eligible users can use SetterVC to track PromptLayer's funding history alongside private-market activity where available.

PromptLayer's disclosed investors include ScOp VC and Stellation Capital. Investor lists are based on public reporting, company announcements, and collected funding-round data, and may be incomplete. Participation in a prior funding round does not mean those investors are currently buying or selling shares. On SetterVC, eligible users can review PromptLayer's funding history, valuation history, and private-market activity alongside other venture-backed companies.

Market context

PromptLayer's most-cited competitors include LangSmith, Langfuse, Helicone, Braintrust, Weights & Biases and Lunary. Investors often compare these companies by sector, product focus, valuation, funding raised, growth signals, investor base, and private-market activity.

Secondary-market demand for PromptLayer shares can be affected by company performance, revenue growth, profitability, funding history, valuation, investor interest, sector momentum, public-market conditions, expected timing of a liquidity event, and the availability of shares for sale. Demand can also be affected by transfer restrictions, company approval rights, right of first refusal processes, limited information, and the price expectations of buyers and sellers. Strong demand does not guarantee strong pricing, liquidity, or investment returns. Weak demand does not necessarily reflect the company's long-term prospects. Demand signals should not be treated as a recommendation or prediction of investment performance. Buyers and sellers should treat demand signals as informational and conduct their own diligence before transacting.

Selling and transaction mechanics

Sellers often rely on intermediaries and platforms, such as SetterVC and other secondary-market platforms, to identify potential buyers. The exact process varies by company and transaction, but sellers often begin by confirming their ownership, desired price, transferability, and any company approval or notice requirements. If the seller agrees with a buyer on acceptable price and terms, the company may need to be notified through a share transfer notice or similar process. If a right of first refusal, company approval right, or other transfer restriction applies, the seller may need to wait until that process is completed. The parties may then execute a purchase and sale agreement, complete required transfer documentation, and close if all required conditions are satisfied. Sellers should always seek proper legal and financial advice before completing the transaction.

Yes, current and former PromptLayer employees, early investors, and other existing shareholders may be able to sell vested shares before an IPO through a private secondary sale. This is not automatic; it depends on whether the shareholder has transferable shares, whether there is buyer demand, and whether the company's governing documents permit the transfer. Many companies require prior notice, company approval, or a right of first refusal before shares can be sold. Sellers should also seek proper legal and financial advice before proceeding.

A PromptLayer secondary transaction usually involves an existing shareholder selling shares to a buyer before a public listing. The buyer and seller typically agree on price, number of shares, share class, and closing conditions. The seller may then need to notify PromptLayer through a share transfer notice or similar process. If PromptLayer or existing investors have approval rights, transfer restrictions, or a right of first refusal, those steps may need to be completed before the transfer can close. The parties typically enter into a purchase and sale agreement, complete any required transfer documentation, and close only if the necessary conditions are satisfied. Timing and certainty can vary by company and transaction.

In most private secondary transactions, parties commonly use a purchase and sale agreement that outlines price, terms, and conditions. They may also use share transfer documentation, often a stock transfer notice, share transfer notice, transfer instruction, or similar document, along with any required company approval or right of first refusal materials. Proof of ownership, such as a cap table entry, share certificate, brokerage statement, issuer confirmation, or administrator confirmation, may also be important. Buyers often request recent company financials, but private companies may limit disclosure. Since every deal varies, buyers and sellers should consult legal and financial advisors to understand which documents are needed.

Risk, diligence, and investor caution

Buying PromptLayer shares pre-IPO is risky. Shares are illiquid, no IPO or liquidity event is guaranteed, valuations can change, transfers may require company approval, and private companies may provide limited financial disclosure. Be prepared for total loss. SetterVC and Setter Capital do not provide due diligence, legal, tax, accounting, valuation, or investment advice. Buyers must conduct their own due diligence, verify information, and seek independent legal and investment advice before proceeding.

Private secondary shares are typically illiquid. Unlike public stocks, there is no active public market, so selling them can be difficult and time-consuming. Sales depend on finding a willing buyer and often require company approval. Investors should be prepared to hold the shares for an extended period, with no guarantee of a future sale. Always assess your need for liquidity before investing.

SetterVC and Setter Capital do not provide due diligence, legal, tax, accounting, valuation, or investment advice. Buyers must conduct their own due diligence, including verifying ownership, transferability, legal structure, company approval, and assessing the company's prospects. SetterVC and Setter Capital do not provide advice on whether an investment is good, what price to pay, or what the best bid or ask is. SetterVC and Setter Capital may share documents in some circumstances, but it does not guarantee their accuracy or completeness. Due diligence is essential. Seek legal and investment advice as needed.

Before buying PromptLayer shares, a buyer should try to review the share class, price per share, implied valuation, transfer restrictions, ROFR process, company approval rights, seller ownership evidence, recent financing or tender-offer information, available financial information, information rights, resale restrictions, tax considerations, and expected liquidity paths. Not all information may be available for a private company. Buyers should confirm available diligence, process details, and information needs with their own legal, tax, and investment advisers.

SPVs carry risks. Examples include the need to confirm the company allows SPV-based transfers, verify that the SPV truly owns the shares or interests it claims to own, and ensure it has not sold more interests than it holds. Due diligence is essential. Seek legal and investment advice as needed.

Forward contracts carry risks. Examples include the seller refusing to transfer the shares at the future date, even if the seller owns them, the seller going bankrupt with creditors claiming the shares, or the seller committing the same shares to multiple parties. Due diligence is essential. Seek legal and investment advice as needed.

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