Free-offer comparison
Free Prompt Engineering Tools
Prompt experiments, evaluations, and trace storage may have separate quotas. Check which step of your workflow the free plan covers.
Guide updated Sep 19, 2026 · Offer review and source dates appear below · Methodology
Free-offer ranking
Each row describes the provider’s recorded free offer, which may cover a different product from the category shown here. The table keeps published units separate. “Not confirmed” means we lack evidence for that detail; it does not mean the provider requires a card.
Scroll horizontally to compare every column.
| Rank | Provider | Free-access score | Recorded free offer | Access pattern | Billing/card | Offer note | Full review | Official source |
|---|---|---|---|---|---|---|---|---|
| #1 | Braintrust | 100/100 | Gateway model credit: $10 credits per month; Processed data: 1 GB per month; Scores: 10,000 scores per month | Recurring allowance | No card confirmed | Token, processed-data, and evaluation allowances have separate limits. | Jul 17, 2026 | View pricingAccessed Sep 13, 2026 |
| #2 | Langfuse | 100/100 | 50K units/mo | Recurring allowance | No card confirmed | A billable unit can be a trace, observation, or score; underlying model charges are separate. | Jul 17, 2026 | View pricingAccessed Sep 13, 2026 |
| #3 | Parea AI | 90/100 | 3K logs/mo | Recurring allowance | No card confirmed | Free plan includes all platform features, two team members, 3,000 logs/month with one-month retention, and ten deployed prompts; no card required. | Jul 17, 2026 | Visit provider websiteAccessed Jul 17, 2026 |
| #4 | Helicone | 75/100 | 10K requests/mo | Recurring allowance | Not confirmed | Underlying model charges are separate. | Jul 17, 2026 | View pricingAccessed Jul 17, 2026 |
| #5 | Maxim AI | 75/100 | 10K logs/mo | Recurring allowance | Not confirmed | Development evaluations are included; production online evaluation requires a paid plan. | Jul 17, 2026 | View pricingAccessed Sep 13, 2026 |
| #6 | Portkey | 75/100 | 10K logs/mo | Recurring allowance | Not confirmed | The free plan is not intended for production, and underlying model usage is billed separately. | Jul 17, 2026 | View pricingAccessed Jul 17, 2026 |
| #7 | Traceloop | 75/100 | 50K spans/mo | Recurring allowance | Not confirmed | The hosted Free plan retains data for only 24 hours. | Jul 17, 2026 | View pricingAccessed Sep 13, 2026 |
| #8 | Confident AI / DeepEval | 30/100 | Free tier | Introductory offer | Not confirmed | The hosted Free plan allows five test runs per week; additional runs are locked rather than billed as overages. | Jul 17, 2026 | View pricingAccessed Jul 17, 2026 |
Why these providers appear in this order
We score each provider’s recorded free offer: up to 40 points for recurring or durable access, 20 for a confirmed no-card signup, 15 for a stated allowance, 15 for distinct evidence links, and 10 for documented terms. Missing details earn no points. Ties favor longer-lasting access, then more detailed records, then provider name. The score does not measure product quality or whether the free offer covers this category. Read the full method before treating it as a recommendation.
Which providers are included?
We include active directory records tagged for prompt engineering tools. A tag describes a provider’s capability; its recorded free offer may cover only part of that provider’s catalog. Check the model or endpoint in the provider’s terms before building on the allowance.
See the full prompt engineering tools category, including records excluded from this guide.