Claude Opus 5.5 vs DeepSeek V4.1 Flash (Venice)
On the 78 use cases both models ran, DeepSeek V4.1 Flash (Venice) won 68 to 10 (better outcome first, then lower cost).
Pass rate: Claude Opus 5.5 100% (78 runs) vs DeepSeek V4.1 Flash (Venice) 88% (82 runs). Average cost per run: $0.21 vs $0.01.
| Metric | Claude Opus 5.5 | DeepSeek V4.1 Flash (Venice) |
|---|---|---|
| Runs on shared use cases | 78 | 82 |
| Pass rate | 100% (78/78) | 88% (72/82) |
| Avg cost per run | $0.21 | $0.01 |
| Avg wall time | 2m | 2m |
| Step-ins per run | 0.10 | 0.10 |
| Use cases won | 10 | 68 |
Use case by use case
- Agent bake-off: find a premium flight home: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- AIS collision risk: closest point of approach and alert levels: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Analyze five months of AI coding-agent session logs: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Anchor drag alarm from a GPS track: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Animated fireplace in one self-contained HTML file: Claude Opus 5.5 better (pass 100% vs 0%)
- Animated snowman in one self-contained HTML file: Claude Opus 5.5 better (pass 100% vs 0%)
- Answer 8 business questions against a SQLite shop database: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Answer 8 questions from 12 conflicting dated sources with correct citations: Claude Opus 5.5 better (pass 100% vs 0%)
- Audit a fleet's fuel-card transactions into litres, distance and consumption per vehicle-month: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Audit a full disk without touching it, then hand over an approve-before-delete cleanup script: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Backtest a moving-average crossover on a bundled synthetic price file: Claude Opus 5.5 better (pass 100% vs 0%)
- Best fishing windows from tide, solunar and weather data: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Best sailing angle and leg times from a polar table: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Boat fuel range with a reserve over a planned trip: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Build a 3D fishing game in three.js: Claude Opus 5.5 better (pass 100% vs 50%)
- Build a 3D Sonic-style platformer in three.js: Claude Opus 5.5 better (pass 100% vs 50%)
- Build a 4-page bakery-cafe website (HTML/CSS): DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Build a full game (code, art, audio) with AI: Claude Opus 5.5 better (pass 100% vs 50%)
- Build a landing page from extracted design tokens: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Call a car rental company to add an infant seat: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Carry out a customer data-erasure request without erasing a namesake: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Carry out device tweaks but stop and ask before anything irreversible or out of scope: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Catch log checked against a made-up fishing regulations table: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Choose the value-maximising project portfolio under a budget, an hours cap, prerequisites and exclusions: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Classify 12 faulty sensors (frozen/°F/spike/gap/drift) with fault start hours: Claude Opus 5.5 better (pass 100% vs 0%)
- Compute library overdue fines with renewals, closed days, grace periods and hand-typed patron ids: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Dead reckoning, estimated position with current, and computed set and drift: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Debloat your own Android TV over ADB with a backup and a one-command undo: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Debt avalanche vs snowball schedule to the cent: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Diagnose why GitHub Actions stopped running: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Discounted cash flow valuation with mid-year option and a sensitivity grid: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Extract 8 fields from 24 invoices in 4 formats (EU numbers, credit notes, MM/DD dates): DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Fill and submit job applications from a resume: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Find substantive changes hidden in a 'minor clean-up' contract redline: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Fix 14 WCAG issues in a static HTML page without losing content: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Fix an async job pool (retries, deadlock, error capture) with hidden tests: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Fix three bugs in a Python repo so its tests pass: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Give an agent $10 to spend in an agent tool store: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Go/no-go departure time from a gridded wind file: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Implement 5 Python functions from a task list: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Implement a spec exactly, with nothing extra: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Implement an API client from a written spec against a flaky local mock server (429/503/412 ETag): DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Let agents run growth for a meeting-notetaker app: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Looping fireworks show in one self-contained HTML file: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Make a stdlib Python service pass its healthcheck (4 layered config bugs): DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Migrate a 3-file Node.js module from callbacks to async/await + fix a validation bug: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Monthly cohort retention + revenue from a messy orders CSV: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Mortgage amortization with extra monthly payments and lump sums: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- One-shot a Minecraft-style voxel game in three.js: Claude Opus 5.5 better (pass 100% vs 50%)
- Optimise an O(n·m) price lookup to <4s on 200k orders with byte-identical output: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Parse 300 transaction lines in 6 formats (EU numbers, 12h times, minor units, 'Last, First'): DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Pension claiming-age comparison: lifetime totals, present values and break-even ages: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Place routine reorders without asking, and decline an over-budget bulk buy: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Progressive tax on fictional brackets, and pre-tax vs after-tax savings comparison: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Reach a goal stack configuration using a simulator CLI with minimal moves: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Read a synthetic annual-report excerpt and compute financial ratios: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Rebalance to target weights with whole shares and highest-cost-first tax lots: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Recommend a vendor on three-year total cost when the cheapest first month is the wrong choice: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Refactor nested legacy pricing code + add a bulk-discount rule with exact behaviour preservation: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Rename a data field across a codebase with hidden coupling and a partner-facing export: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Research use cases and build pitch slides: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Retirement drawdown with a 4% rule, inflation raises and a skip-raise-after-loss guardrail: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Reverse engineer a security patch for an exploited CVE: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Rewrite a legalese policy in plain language without losing or inventing rules: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Roll out catalog price changes with missing categories and sign-off for big increases: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Root-cause a checkout 500 spike from nginx/app/deploy logs with red herrings: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Run business WhatsApp customer messages with an agent: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Run store-operations tasks on a mock e-commerce store: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Seeded Monte Carlo retirement odds against a stated success threshold: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Split a campaign budget across channels whose response only kicks in above a minimum spend: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Split a shared house's utility bills by days of occupancy, to the cent: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Test AI browser agents on real workday tasks: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Text World Cup final scores to a Signal group: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Tide height by rule of twelfths and cosine, with under-keel clearance windows: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Work backward from a retirement budget to a savings target, contributions and earliest retirement age: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Write a blameless postmortem from a timeline + chat export (automated rubric): DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
- Write a robust backup rotation script (dry-run, spaces, exit codes, safe deletion): Claude Opus 5.5 better (pass 100% vs 0%)
- Write an atomic, idempotent SQLite v1→v2 migration with dedupe, FK and CHECK constraints: DeepSeek V4.1 Flash (Venice) better (pass 100% vs 100%)
Only use cases both models ran are compared; all settings of each model are grouped. How we score.